13 Sentinels: Themes and Characters (Spoilers)

Exploration of Sekigahara, Shinonome, and Fuyusaka. This post compiles analyses and notes written over several months. I tried to revise and edit them to make the text more readable, but it is still inconsistent and full of errors. My interpretations were based on the original Japanese script. I also read interviews and other supplementary materials.

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I always thought George Kamitani gave Sekigahara Ei too much spotlight in the game in comparison to any other character. Sometimes he looks like nothing more than a plot device, while other times he gets some decent writing. Sekigahara appears in almost every route, often triggering events and pushing the story forward while leaving behind vague hints before disappearing. You could even say he seems to be working more for Kamitani than for Ida himself, since most of the time what he's doing before amnesia makes no sense, and it's kind of funny to me. I think the writer took advantage of the fact that he can move freely, has a lot of knowledge, and shows only a mild case of DD426. It was an interesting choice, especially considering that Sekigahara in 2188 was only in the colony to watch the world burn. Going from being the most useless in 2188 to one of the most active in the present is a clever choice, whether it was intentional or not..

Sekigahara’s story is one of the hardest to understand, and I enjoyed piecing it together. Felt like I was playing the game as intended, a puzzle narrative. He’s the kind of character whose appeal comes more from how the story and its events impacts him and how he reacts to them. He doesn’t have a very strong personality, but that may be intentional, like he’s just a normal boy caught in a situation that goes beyond his control.

Watching his scenes in chronological order is really helpful. For example, you start to notice that each time he visits Fuyusaka, something important has happened previously, and his psychological state changes, gradually becoming worse

Sekigahara grew up not being very good at socializing. Since his parents were rarely at home, he became attached to Shinonome, his neighbor, who was probably the one to approach him first. Based on extra material, both of their parents wanted to separate them, worried that he might be in love with her and that he could be a bad influence. In response, he became a troublemaker. While Shinonome, who only saw him as a younger brother, decided to date Gouto to reassure her parents.

She also did this because she wanted Sekigahara to open up to others, which suggests that she had become his entire world. Sekigahara, who secretly admired Shinonome but never had the courage to confess, was heartbroken. Over time, he moved on, came to see her more like a sister, and simply wished for her happiness. I imagine she was his "first family", his first friend...his first everything.

If I’m not mistaken, Kamitani said Shinonome fell in love with Ida because she liked to deal with her problems on her own, and he was the only one who noticed that and supported her, reassuring she could always rely on him. Deep inside, I think she somewhat craved validation. I know Shinonome post-infection is unreliable, but before shooting Ida, she mentioned not minding being used and she shot him for being in love with another girl. She became emotionally dependent on him and lost her sense of self. Without Ida, she probably felt like nothing and his validation was what kept her alive.

I’m bringing this up because I assume Sekigahara, even though he was only a year younger, was much more passive and immature than her. He relied on her a lot and simply followed her blindly, without really giving her the same kind of support she gave him. I’m not saying he caused her situation with Ida, but it does make me think about how she may have been missing that kind of support, which made her vulnerable to Ida.

Shinonome was the one taking action to keep their parents from separating them, while he stayed passive and even threw tantrums. Despite being a cute dynamic, she was too young to take care of a boy just one year younger. I think she eventually grew tired of his dependence on her and wanted him to live more freely, building his own life, making his own choices, forming new friendships, and falling for other people. She wanted him to step out of his comfort zone and have the courage to take action and face things directly... And Fuyusaka is like that, sincere and true to her own feelings, she lives facing reality.

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About Fuyusaka… oh, she’s so silly. The way she was intentionally made to know very little is both interesting and a bit funny. And yet, she still manages to move the plot forward just by being herself. Through her ID, Prof. Morimura exists; her and Tomi’s friendship with Miwako softens her and leads her to save the citizens and help them escape the simulation; and Sekigahara, influenced by her, ends up stopping Ida and joining the battle.

Kamitani said she represents the “adolescence” phase of Morimura and contrasts with the colder nature of her adult versions. Since Fuyusaka’s personality is so straightforward, pure, and unguarded, her side of the romance and her route ended up being too. It really parallels Sekigahara, who overcomplicates things, tried to do morally questionable things, leave vague messages, have difficult making choices, is reluctant to embrace love and is stuck in the past. Whether it was intentional or not, it was still interesting seeing.

Personally I was caught by surprise with her boldness and assertiveness, she looked shy, "coward" and passive at first glance. Similarly to Sekigahara, who looked cool and brave, but is more "coward" and shy. I like these type of contradictions (gap moe?).

Despite being characterized as just a normal girl, she has some quirks, like wanting to put dumplings under her bra (what?), along with other funny lines and her romance also have some rom-com elements despite having a bittersweet tone. I like that she seems to be both the boke (the fool) and the tsukkomi (the serious one) in light-hearted scenes.

Despite being somewhat transparent, her personality is nuanced enough to make her feel internally alive. She’s introverted and introspective, shy yet assertive, diligent yet a bit lazy, dreamy yet grounded, and thoughtful yet a bit airheaded and impulsive. She also seems to have a thing for stealing keys (ˆᗜˆ), and seems capable of lying quite convincingly when she believes it’s for a good reason.

She has average grades and seems to struggle with some subjects, like math (she said it puts her to sleep), but excels in others (biology? physics?). For someone who sleeps so much and still gets those grades, does she have some kind of genius in her genes? Speaking of genes, Izumi mentioned that Morimura said she loved him from the first time they met. I guess Morimuras are romantic by nature, but Nurse grew up more cold and rational. She delayed confessing, failed to get Juro back, and died regretting not being able to be with him.

I noticed that Fuyusaka, despite being very straightforward when it comes to acting on her feelings, seems a bit skeptical when it comes to things like aliens, her dreams being real, memory transfers, and advanced technology. Her sense of identity must also be very strong, since she seems to have received the largest number of memory transplantations and still seems relatively fine. Amiguchi only received one. She received seven (are you really okay?).

I may be stretching this, but Morimuras and Fuyusaka seem a bit crazy when it comes to making decisions. The Morimuras are shaped by rationality, yet they seem to act in this determined, almost reckless way, like they’re driven by irrational logic. And they seem unstoppable. Like becoming obsessed with Project Ark and selling nanomachines on the black market despite being a genius, or Nurse deleting "her" logs and everything with it after learning that her original self in 2188 exterminated humanity and later being very persistent with the Aegis Plan.

It feels like Fuyusaka takes that same kind of craziness into her own lifestyle. Anything her heart wants, she goes for it, whether it’s seeing a cat she’s never seen before, confessing to a mysterious boy, or jumping into a mecha battle she knows nothing about, with no allies, no plan, or even knowing how to pilot. All of this makes me think she seems drawn to anything unusual or very mysterious, as she likes strange things, like banana with mayonnaise crepes (I'll pass this).

While Sekigahara continues to go back to her and support her after saving her from Wajima, her first impression still leaves room for interpretation. He could simply be the type she’s naturally drawn to, as she describes him as 素敵, which can mean charming or lovely, like someone with a pleasant aura. Later, we don’t really get more of her thoughts about him, aside from her cloud link, 気になるの彼, meaning "the boy I'm interested in" or “the boy I’m curious about.” I do think she was drawn to his mysterious presence, as he appears in unusual places and even knew her name. Even though I can only make guesses, there’s something intriguing about not knowing exactly what initially drew her to Sekigahara, and her own uncertainty makes it feel unexpectedly immersive and human.

I do think Sekigahara got inspired by and fell in love with this part of her, and is meant to balance out that craziness and help her stay more grounded. Living that impulsively can be dangerous (ˆᗜˆ). In a way or another, both can be mysterious people.

She’s the most immersive character to me. She appears in most of the routes, living her ordinary life while interacting relatively well (for this game’s standards…) with the narrative and the other characters. It felt like she truly belonged to the world, like she actually lived in Ashitaba and didn’t “disappear” when she wasn’t the focus of her own story.

It was her route that properly presented Ashitaba City to us and showed how life there really felt like an actual city. That was very important to me, since I value immersion in stories. Her story shows how AIs are just like real humans, and Miwako represents the 1.2 million inhabitants they were fighting to protect. From the school to the neon-lit city, studying (or sleeping), going out with friends, eating, and living her youth to the fullest. This is what she fought to protect and that feeling was very palpable to me. Anything that happened in that world really felt it would impact her and she was genuinely reacting to the end of the world in her story's last part.

I also found it pleasant to immerse myself in the eyes of someone living confused between dream and reality; her route has a heartwarming tone mixed with some eerie vibes and a strong nostalgic atmosphere, very 80s. Like the shoujo manga it was mostly based on, it is very sentimental and has strong symbolism for the players to figure out and is very representative of the game's themes. Has a good setup, starting very calmly with a vibe of "something is wrong" and escalating till we feel a good sense of urgency.

Her character, personality, love story, and route were among the most authentic, sincere, and earnest things I’ve seen in a while. I admire the author’s bold approach, as ironically it takes courage to embrace this kind of storytelling nowadays. Well, 13 Sentinels is already a risky game...Kamitani and Fuyusaka seem to share that same traits. She was the character I connected with the most when she activated her mecha, and in Destruction Mode, I always tried to keep her on my team.

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Through Fuyusaka, we can infer that Sekigahara realized what he needed to change after being pushed through extreme failures, wrong decisions, and a lot of misery porn: Ryoko being successfully manipulated and straining their relationship; the destruction of his hometown; Ryoko’s memory issues causing her to try to kill him, and him being unable to reveal it's her fault; her losing memories; working with Ida; the MIB chasing him all the time; betraying his friend; accepting to eliminate anyone in his way; trying to destroy an entire world; his own headaches and future amnesia; the risk of becoming a husk; and finally, learning that he was a clone of an actual hitman.

I would say he was going through his development after the Kaiju attacks and started making his own decisions. Like he told Fuyusaka: he owed Shinonome a lot and wanted her to be happy. He took the role of an older brother after Ida showed up and tried to fix the situation, but he did that in the wrong way. Decisions come with risks, you need to understand their consequences and take responsibility for them.

The park scene with Morimura happens after he finds out his plan was leaked and that Miura AI and everyone else knew what he was working on for Ida. That’s when he starts to become incredibly vulnerable and self-loathing. He leaves the park feeling even worse after realizing he can’t even run away anymore. Later, after Shinonome finally loses her memories and he contacts 426, we see him giving his mecha to Fuyusaka, saying it’s better in her hands. And indirectly praising her determination and courage. Even though he knew the mechas could be used again, he still didn’t want to fight or do anything anymore. Sekigahara regretted his choices and kept running away from them, since he had failed before and he saw no reason to try again.

Following my emotional logic, I never thought that only seeing a video of his past-self being an hitman would be enough for this lonely child to find the courage to fight kaiju and face an empty future. Rejecting your past is different from accepting a future, especially when you have nothing. So I think the determined girl he met inspired him to face things directly. Fuyusaka also shows awareness of her impulsive nature and the dangers of acting on it, yet her heart is just… unstoppable. (◡̀_◡́)ᕤ So he embraced his amnesia or a possible death, prepared messages to himself, accepted his mistakes and showed them to his future self, cleaned the mess he made by taking down Ida, reciprocated Fuyusaka and went for the battle.

I believe that meeting Fuyusaka and seeing her care for her hometown, family, and friends gave him a second chance. I also believe he saw himself in Fuyusaka when he was trying to save his city. When she refused his offer to run away, Sekigahara seemed surprised by her determination to fight. Despite knowing things could go wrong, because she carries Morimura’s memories; has seen Sector 3’s ruins; knows her life is a lie; and knows she could die, she still chooses to fight. It’s only when both Morimura and Sekigahara refuse to fight, with Sekigahara leaving the park in distress, that Fuyusaka begins to be affected by their cynicism. Morimura and Sekigahara are both individuals who, after a series of failures, became more pessimistic and jaded. You could kind of call them "cowards." While Morimura kept like that till death, Sekigahara embraced his second chance and overcame it.

By the way, in Kurabe’s route, there’s a scene after the park scene where Fuyusaka, distressed by the news of the Kaiju attack, tries to ask him for help. She explains that their dreams were actually real events and that an attack is coming. However, Kurabe, being manipulated by 426, doesn’t take her seriously. She leaves him apparently annoyed(ˆᗜˆ).

Based on his story's final conclusion about deciding to fight for a future with Fuyusaka. I see it as him reaching the same decision both before and after losing his memory. He chooses Fuyusaka’s path twice. I think the pre-amnesia Sekigahara wanted his future self to make his own decision. The only clue he left about Fuyusaka was her ID. I do think he hoped his new self would choose her again.

Much like Ryoko with Amiguchi, in his route he mentions having strange feelings when looking at her picture but tries to interpret them as having memorized someone who was very dangerous. Over time, he starts to like her again. When he finally recovers all of his memories, these new feelings add to the old ones, and he ultimately chooses her, leaving his past behind. Later, we can see him praising her sincerity with her own feelings when she fights, before joining the final battle himself. I believe the night Fuyusaka confessed to him was very important. Being one of the reasons he backed up his memories and never fully rejected her. Deep down, hope never completely left him. (( ◡̀_◡́)ᕤ

To me, their romance feels like an inspiring coming-of-age story about being true to yourself. It’s about not letting the past dictate your present but instead continuing to move forward, trying new things with the hope that they’ll work out while also accepting that they might not. The future is unknown. The unknown can feel mysterious, frightening, and captivating, and it takes courage to face what you’re afraid of. His line: "If I had the courage to choose you, it would've been the best thing" seems to represent that.

This scene and the bike logs can suggest that one of the themes in this romance is "choice." Fuyusaka tends to make quick, decisive decisions, while Sekigahara does not. When he discovers that Fuyusaka is Morimura, he is faced with two options: either try to stop the Aegis plan through morally questionable actions, such as killing Morimura and Fuyusaka and then running away, or choose not to interfere, remaining clean, but ultimately cornered by having to face his harsh reality.

I believe that after Fuyusaka’s confession, his failures, and the park scene, Sekigahara comes to see that the second choice has always been the better one. Now it includes accepting his growing feelings for her and a chance to live an unknown romance in an uncertain future. He needed courage to be hopeful and more dreamy, and courage to accept any bad outcome that come with it. So he embraced his amnesia or a possible death, prepared messages to himself, accepted his mistakes and showed them to his future self, who cleaned the mess he made by taking down Ida, reciprocated Fuyusaka, accepted any future and went for the battle.

Ah, I keep forgetting the killer/target theme. They reforced these themes by defying their fates. Fate brought them together, but due to the way they were nurtured, they fell in love instead. The clone of the woman who once influenced "him" into becoming an assassin now helps Sekigahara, who was stuck in a dilemma, to choose a better path. And instead of using his weapons to harm her, Sekigahara chooses to admire, protect, and support her. Sekigahara lacked the courage to fight but had the tools. Fuyusaka lacked the tools but had the courage to fight. In the end, they exchanged what the other was missing.

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Sekigahara's personality when he isn’t under stress is hard to grasp. Scenes like Izumi’s death or Natsuno’s disappearance suggest he may be more realistic or cynical, possibly shaped by his past failures. There isn’t much context. From what we can tell, he likely wasn’t always like this, as he seemed more confident that they would succeed during the battle in Sector 2.

To me, he comes across as someone who looks cold on the outside but is actually very sensitive, calm, and kind-hearted. based on his actions and the things he says to Fuyusaka, I’d even like to think he’s the most romantic out of the boys. Throughout the story, we see him helping several characters, and some of them return the favor, like Takamiya and Natsuno. I think he is just bad at wording things and too quick to point his gun. He was so rude to Takamiya when she offered help (going after Ida and the MIB alone wasn’t a very smart move). He seems to only show a softer or emotional side when things get extreme or when people push him to open up. Romantic feelings seem to be the hardest for him to express. He only calls Fuyusaka by her name in pinch situations during Destruction Mode, and he mainly shows his feelings through actions rather than words. Either Shinonome was clueless or Sekigahara was really good at hiding his crush from her when he was younger.

He also seems to treat gentle people much better than the rude or loud ones, which implies his tastes and his own personality. But I do think sometimes the swings between cold and soft are too "wild," making his character a bit artificial. Nobody changes so much based on the others' kindness (ˆᗜˆ). I personally don't like him very much in Destruction Mode, his appeal came from the Story Mode.

I confess I had some secondhand embarrassment from some of his actions, like invading Kurabe's house, that smug log Ida he showed him, or the excessive cryptographic messages he recorded to himself, as if he were trying hard to look as cool as Schwarzenegger. We also can see some really silly side of him, like blushing at Fuyusaka and Okino (Kiriko) or pulling out a gun in front of a cop. All of this added a bit of goofiness to him that helps to break his stoic aura. And honestly, I think he's unintentionally funny. There's something really funny about him to me (ˆᗜˆ). Imagine someone who looks so cool and smooth while carrying out a secret mission, only to find out that all the people who shouldn’t know (Morimura, Gouto, 426, and Miura AI) already do, because he’s just that bad at lying. In a way, his inability to lie adds charm to him. It makes him more clumsy and honest. He seems really socially awkward and not that cool at all.

I think he may be much more immature than he looks. Sometimes, he can come across as petty, like in the scene where Shinonome doesn’t share what she discussed with Ida. With Gouto, in Destruction Mode, he was acting like an annoying, overprotective little brother. In Sector 3, we saw him being a bit rude and sarcastic to Shinonome, who is trying to kill him. He even left her alone to take care of his business, which was a bit funny to me (she is not okay alone!(ˆᗜˆ)). Sekigahara's writing is a bit inconsistent, but unfortunately, it is natural to lose patience with Shinonome's situation. They probably had that type of conversation multiple times...it was probably exhausting.

In my opinion, his interactions with Shinonome are when he seems the most natural and relaxed, which makes sense given how familiar they are. The scene below shows him speaking in his kindest tone of voice, and together with his words, I think the sadness of this scene comes from both him and the soundtrack. While I felt bad for Shinonome, I think Sekigahara had it worse, since he finished the game remembering everything he lost...

Next is Fuyusaka. Nothing too overly polite, nothing too rude, and not just a “plot dump” either. Even though he tries to keep some distance, I believe he still feels comfortable around her. He’s still struggling to express romantic feelings with words, and he isn’t as open with her as he is with Shinonome, who is (or was…) his childhood friend. But in scenes with Fuyusaka, he is vulnerable and soft, while also being straightforward and honest. During her confession, he even sounded a bit flirty and playful to me. With other characters, he looked too guarded or just focused on moving the plot forward. With Miura AI, he looked artificially friendly and polite (sorry for the negativity here (つ╥﹏╥)つ). Now with Tomi, Okino, and Hijiyama, I actually feel like there’s potential for him to grow closer to them, especially Okino. I don't know why. Maybe it’s because they’re the type of people who can pull him out of his seriousness.

As for Gouto, I find their relationship particularly interesting, while Sekigahara doesn't like him because of the misunderstanding regarding his envolviment with Shinonome, previous partnership with Morimura and presumably his "pompous", popular and cold person, Gouto seems to know him very well. His commentary to Dr. Morimura about knowing he was just a very brooding guy and not stupid enough to shot someone impulsive was very surprising and reassuring. I don’t know why, but based on this, I could interpret that that Gouto was never worried about Sekigahara and his partnership with Ida, because deep down, he knew true Sekigahara would never go through with it. It would be interesting to see what will become of them in the future.

He also shows a kind of awkward, dry humor in that flashback with Miura AI. Regarding them, while this friendship worked on a surface level, but the more I thought about it, the more it felt a bit off, and I started to regret it. I never really saw what made them so close, so Sekigahara calling him 親友 (close friend / best friend) in his story felt kind of empty. For Sekigahara, I feel like I need to actually see someone break through his walls. Miura is earnest, but his polite, duty-focused nature makes him feel… distant? I had trouble understanding how someone as closed-off as Sekigahara, or even I, would naturally befriend him. Maybe I’m projecting.

To me, it might have been better if he had taken on more of an older brother role and chosen on his own to show the 2188 logs to Sekigahara, wanting to give him a needed reality check rather than waiting until he was begged. As it is, it feels like he just ends up enabling Sekigahara’s flaws. Sekigahara, alongside other struggles, was being chased by MIB just to trick Miura, but Miura's response was just to erase his memories, leaving him lonely and lost. Miura AI has knowledge and agency but doesn’t seem to actively support Sekigahara like how he does Natsuno or Hijiyama. It's like he was really focused on uncovering secrets and saving a world that, logically, doesn’t mean much to him. Felt like their scenes were carried by my pity for Sekigahara and a sense of nurture for Miura AI's vulnerable drone body. Once the vision is not here, I sense a writing disconnection because there is a real person inside it.

I wished we got more real conversations between them and not just those mascot/owner dynamics. The logs he wanted to protect so much weren't even useful inside the simulation. I guess he was just afraid Ida would erase them. But Ida thought the logs were with him, so them being on No. 17 was actually safe. Maybe the actual intention was for it to be a fleeting, flawed friendship. Oh, really sorry for the negativity here again (つ╥﹏╥)つ. At this point, I wonder if I'm nitpicking.

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About Shinonome, even though I liked her, I never really understood her bandages and memory issues. The bandages were probably meant to be symbolic, to emphasize her poor condition, since it doesn’t really make sense for her to be the only one hurt in Sector 2. As for her memory, I’m not sure. She even remembers that 2188 log despite having total amnesia. Kamitani certainly wasn't paying much attention to these detail.

Shinonome’s story tries to put the player in the shoes of a confused, amnesic girl. We’re constantly taking pills, and there’s a strong sense of urgency. It feels very different from the other routes. It ends with her being the actual culprit, similar to the movie it was inspired by (I don’t want to spoil it). But while the movie has an ambiguous ending, her story ends with her clearly having no memories and still fighting for Ida. And her journey doesn’t really stop there. Someone told her the truth about Ida, because based on her skills, she apparently was fighting to atone for her sins and not for him anymore. I don't think it was Sekigahara. Maybe it was Gouto? Morimura?

Anyway, in the end Shinonome's actual personality is a bit confusing. In Destruction Mode, she seemed robotic, unnecessarily rude, and full of mechas/deimos dumping exposition dialogues. Before her amnesia, besides the occasional bad temper, we could see a softer side. For example, she acts happy and docile toward Kurabe, thinking he is Izumi. We can also see her tendency to handle things on her own, as she turns down help from everyone. Honestly, it’s kind of cute and even funny how she tries to act tough. I believe Shinonome was likely a much kinder and gentle person before meeting Ida, since Sekigahara seemed to admire her so much. That seems to fit with the fact that he doesn’t appear to be like talkative, loud, or rude people. After her amnesia, I think he decided to let her live her new life by herself and decided to watch her from afar. I hope they can bond again.

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Writing this makes me realize how connected Sekigahara and Fuyusaka feel to the world, the narrative, the themes, and the other characters. It’s impossible to talk about them without considering how they react to and shape their surroundings. I think the author succeeded in appealing to me by making everything feel so integrated. (‾◡◝)

Well, I tried to take in everything I could from the author’s intent and what he presented, while keeping his inspirations in mind too. I don’t know if my interpretations are away too far-fetched, but these are the conclusions I arrived at. Most of it I just "felt" during my two playthroughs but couldn't put into words, and now, after writing them I’m think satisfied enough.

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Sekigahara Timeline (Pre-Amnesia)

His pre-amnesia story is confusing, especially his logs. I know he's just there for the plot in some cases, but I wanted it to make sense, so I did this ages ago on my PC while trying to put everything in order, including extra content from interviews. I fixed it to be presentable and added new things. It contains repeated information since I used it to write my previous analysis.

1. As a child of unknown age. Have absent parents (maybe just clueless and/or working too much?). He meets Shinonome, she takes care of him.
2. As he told Fuyusaka, in primary school he got confessed to by a girl (maybe more than one? who knows if he was popular...such important info...).
3. Practiced boxing.
4. Middle school, before September 2063. At some point, their parents try to separate them, thinking he might have romantic feelings for her and that he could be a bad influence. They were right about him, but Shinonome only saw him as a little brother. In response, Sekigahara starts to rebel against his parents.
5. Around September 2063. Shinonome starts to date Gouto. "If I date a guy with a good reputation like him, maybe my parents will stop trying to separate us, and Ei-kun will start to be more independent from me and open up to others" was her thought based on extra materials. It worked, and Sekigahara got heartbroken and decided to see her as family, whishing for her happiness only.
6. Around March 2064 (before graduation), Shinonome breaks up with Gouto after her plan worked. About six months later, in October 2064, Kaiju attacks begin, and they meet Ida and Morimura. Shinonome becomes captivated by Ida and is manipulated by him at school.
7. At some point in October, Shinonome agrees to pilot a mecha. Sekigahara, worried about her, also agrees.The S2 events seem to happen within just a few weeks or even days. How good Ida is at manipulating Shinonome to get her into that state? They meet after the first wave (as shown in Shinonome’s story), but the timing of these events (6–11) depends on how spaced out the waves are in S2. It also makes me wonder how intense the attack in S4 must have been for all the waves to happen in a single day.
8. Sekigahara sees Ida and Morimura talking. He shows interested in saving the city (initially didn’t think he cared much about, but he actually does). He agrees to help update the third generation mechas in exchange for Ida to stop using Shinonome. Despite not liking Ida, he ends up being manipulated into distrusting Morimura and starts to see her as suspicious.
9. He begins updating the mechas and is going to update No. 17. There, he learns that there are logs from 2188 that Miura AI backed up in his mecha before Morimura deleted them. Morimura becomes even more suspicious to him, and he starts to hate her. He promises Miura AI that he will take care of the logs. Miura asks if they are friends before he proceeds with the update, probably to ask him to not go through with it, he ends up not updating No. 17.
10. Still in October, Shinonome installs DD426 into his mecha after a fight. A wave is approaching.
11. Same day. The battle goes wrong. An infection occurs, and everyone becomes separated.
12. Probably on the same day as Event 10, he meets Tomi426 in S1, who says Okino might know how to cure DD426. He gets medicine, but the headaches will eventually lead to amnesia or a vegetative state.
13. He goes to S5 and finds Okino, trying to ask for help. Okino asks if he knows who caused the infection. Sekigahara seems to know it was Shinonome but refuses to say it, so Okino doesn’t trust him and refuses to help. Hijiyama then chases him.
14. (Weirdest scene in the game, probably leftovers of unused plot points. I pretend this scene doesn't exist lol) He meets Tamao, who says Okino told her she came from the future and that her parents aren’t her real ones. Then he meets Miura and somehow tells him that Miura AI is from the future and is inside a drone, even though he shouldn’t know that yet (Ida only tells him later). It really breaks immersion. Still, this scene shows him starting to lose patience, unable to trust anyone, and mentally deteriorating. I think it is the moment he starts losing his innocence and moving closer to his past self… pointing guns at everyone
15. Trigger Hijiyama's route by taking him to S4 while chasing Okino
16. Goes to S3 and gives medicine to Morimura for the others
17. Meets Ida. Gets knowledge about loops (which he interprets as different “worlds”) and the existence of another world in 2188. Ida wants to destroy this world to loop. To save himself and Shinonome, Sekigahara agrees to work with him: secure the battle fails and this world get destroyed, retrieving the 2188 logs from Miura AI, and killing Morimura and anyone in the way. He reunites with Miura AI and starts lying to him (with a terrible voice tone in jpn btw, he really sucks at lying). From this point on, he helps search for No. 17, which contains most of the logs.
18. Around February/March 1985 (Yakushiji was already in S4 in March giving a Yakisoba Pan to Hijiyama). He meets Yakushiji and sees Izumi dying in S3. I don't know why he’s there. Maybe too see the destruction of the sector, look for n°17, or just walking...why not? (ˆᗜˆ)
19. At some point, he backs up his and Shinonome’s data into Sector 0.
20. (Unknown Log 1) Records the smug message shown by Android Ida.
21. (Unknown log 2) Records the prologue message telling his future self to escape this world (loop). Like the other characters, its unclear what he thinks the world is. He doesn’t realize it’s a simulation, but also doesn’t question the existence of looping or time traveling. He probably just didn’t have time to process everything (finding excuses)
22. (Unknown Log 3) Records the bike log reminding himself to stop Morimura and retrieve the 2188 logs.
23. In April, Fuyusaka bumps into him and drops her ID. She looks very similar to Morimura, so he starts investigating her. Was he looking for Morimura here?
24. Still in April, he goes to S2 (his hometown, likely a place he feels safer). Meets and talks with Fuyusaka. Guesses Fuyusaka shares ID with Morimura, meaning they are the same person.He learns she has Morimura’s memories and is gradually becoming her. He hesitates having to kill her. Still suspicious of her, tries to help her. Morimura appears, forcing him to leave.
25. In the science room, he tries to hack the teleporter locked by Morimura’s ID. The system goes crazy and teleports him, Shinonome, Tomi, and others. To make it more natural it could be that Fuyusaka unlocked it with her voice from afar… though that might make it even more convenient (ˆᗜˆ). This event triggers Tomi’s route.
26. In S3, he leaves Shinonome behind, who tries to kill him thinking he is 426. He disappears for a few days and later reappears to help Tomi and the others.
27. In Sector 2, after trying to reach Shinonome, he meets Fuyusaka again and seems still somewhat suspicious of her.
28. Just before May, Miura AI erases his memories at school. Maybe he ran away from Sekigahara to the girls changing room and erased it. Or he erased it first, then Sekigahara had to hide him there because he couldn't walk with the drone or the drone wasn't obeying him and run away. I don't know. Bumps into Natsuno. This will trigger Natsuno's route
29. In the background, he was likely still investigating (or stalking) Fuyusaka while searching for Miura AI.
30. (Unknown Log 4) Possibly recorded after meeting Fuyusaka or after her confession. He confirms she and Morimura share the same ID, and starts to doubt his actions, realizing she might be innocent. Still, he says stopping the Aegis Plan is the right choice.
31. In early May, he saves Fuyusaka from Wajima. When she asks why, he says it was a coincidence, but she says he's lying. Considering how bad he is at lying, he was probably already watching her. Why? To kill her? To investigate her further? To see if she was anything like Morimura?
32. She confesses to him. He’s surprised but happy. He accepts her feelings but doesn’t give an answer. He talks about his past with his parents and Shinonome, and says he’s never been confessed to since elementary school. He mentions they are connected by “entanglements” and promises to contact her.
33. He later meets Takamiya and Miura (now with restored memories) and goes with them to find Natsuno in S2. He hilariously tell them to expect the worst.
34. Takamiya sees him with Tomi426 body
35. He finds Tamao426 dismembered. He tells him Miura erased his memories because his plan was discovered. He thinks it’s a trap from Morimura. Tamao426 calls him a nuisance, he shoots him and leaves. From this point on, he loses confidence and enters in his self-loathing phase.
36. (Unknown Log 5) This refers to only the conversation he had with Miura, begging him to show the 2188 logs. He asks Miura if he really erased his memories because of him. Miura confirms. Sekigahara begs to see the logs Miura had refused to show him and asks him to link them to the current recording. This likely marks the start of his self-hatred phase, especially since everyone (Miura, Morimura, Gouto, 426) already knows about his plan. A walking failure...
37. (Unknown log 6) This refers to the actual 2188 logs. He watches the 2188 logs and finds out he is the clone of an assassin who was also tasked with killing Morimura. Shippo mentions that he probably saw this, and that it shocked him. Either he watched them here and only processed the shock later, or Miura hadn’t shown them to him yet and only linked the 2188 logs to "Unknown Log 5" later, to show to post-amnesia Sekigahara. The scenes of "Unknown Log 5" (and maybe he watching log 6 too) could have happened when Takamiya finds him in a bad state with headaches. In that moment, he asks her to pass a message to his future self in case he loses his memories, so it was probably recorded around then. (Maybe he didn't get to see the logs from 2188 or maybe he did? How agonizing! lol)
38. Quit working for Ida, but Ida obviously doesn't know.
39. At some point, Takamiya finds him in a bad state with headaches. In that moment, he asks her to pass a message to his future self in case he loses his memories. She leaves to save Natsuno.
40. Hijiyama finds him with Miura AI, sees the 2188 logs, and takes him to Okino. He asks Okino to back up his memories because there are things he doesn't want to forget (what things? His mistakes? Fuyusaka's confession? Shinonome and Miura? Everything in general?) but refuses a personality backup, saying he hates himself and doesn’t want to make the same choices. With this mental state makes sense that the conversation with Miura AI, recorded in the "Unknown log 5", really happened between events 36 and 39. Not sure about if he watched the 2188 logs too.
41. He takes Fuyusaka to Morimura. In his self-loathing state, he tries to push her away, but they end up having a vulnerable conversation. He reveals the truth about her life and invites her to run away with him and Shinonome. She refuses and chooses to fight. He learns he can’t even run away, because he would no longer be human. He gets even worse. When Fuyusaka tries to encourage him, he says he doesn’t have the courage to choose her and wants to keep running away. In this scene he threatens to kill Morimura, a strange move if he've already watched the 2188 logs (Unknown log 6). At least to me, I doubt he would be pointing that gun to Morimura knowing he was an assassin in the past, unless he was already that self-destructive.
42. Morimura later calls him to see Shinonome, who has lost her memories. She only remembers him as “Ei-kun” from mecha training. She still chooses to fight thinking of her teacher (Ida).
43. In mid–late May, Megumi tries to shoot him. He follows her and meets Shippo (426), who explains everything and his plan to fight. Sekigahara refuses to fight and instead asks how to transfer his mecha to someone else (Fuyusaka).
44. He seems close to breaking down. Unable to save Shinonome, he makes his final decision: he gives his mecha to Fuyusaka, saying it’s better at the hands of someone like her.
45. Around this point, he likely watches the 2188 logs (if he hasn’t already), breaks down, then inspired by Fuyusaka’s determination, changes his mind and decides to fight for their futures.
46. Shippo mentions he came to him crying and begging to join the battle. Since DD426 detaches the nanomachines, Sekigahara needs to be shot after the amnesia.
47. (Unknown phone messages) He records two messages. I remember reading that when you play them, the last one recorded is actually heard first, I don’t have a source for that anymore. The first one we hear has him telling his future self to choose his own path, forget the past, and look for Miura because he has a message for him. The second one tells him to “finish the job.” Initially, I thought that meant killing Ida, but that doesn’t really make sense if his goal was to let his future-self to make his own decisions. I assume the second message was recorded before his change of heart. So I'll believe the person who sid that the messages are played in reverse order. As for why Sekigahara left all these messages… honestly, it was to confuse himself and the player.
48. He prepares everything for his future self: medicine, Fuyusaka’s ID, keys, and message codes. To avoid Ida finding out, he keeps everything vague and indirect, which makes things more confusing. This is why he confides Morimura the paper and never talks about Ryoko or Fuyusaka in them. Miura AI and Natsuno, Ida already knew them existances.
49. I don't know why, but he meets Morimura. Maybe Ida lost patience and sent MIB to kill her. I wonder if Morimura have always been chased. Sekigahara seems to be helping her escape or maybe they arranged that meeting. He then questions her actions regarding the logs and and ultimately loses his memories.

Trivia + Supplementary Material Info

• Sekigahara seems to have issues with modifying his own body. He doesn’t like the idea of mixing it with artificial elements, which is why he feels uncomfortable with things like backups, simulated personalities, or becoming an “illusion” like Morimura. I wonder if he also disliked having nanomachines in his brain. He seems to be fine with other people or AIs tho. This plot was never touched again, so it might be a dropped idea or just not that important, or maybe he simply got over it since he did the backup.
• Nurse Morimura gives Sekigahara a lot of attention: she gives him a bike, shares secrets, and seems to trust him despite him working for Ida and even trying to kill her. At the same time, she appears more distrustful of Shinonome and Gouto. Did she have a crush on him?(ˆᗜˆ)
• Sekigahara backed up all his memories and 30% is just the scan area. Sekigahara had multiples trips to Okino. He scanned everything, then when the D-code detaches it backs up the memories. This is how I interpreted.
• Fuyusaka’s activation line about being an “Invincible High School Girl” is a callback to Tomi saying something similar during one of their eating sections. Tomi later says something like that again to Megumi in Destruction Mode, about the “power of high school girls.” I tried to find if this is a reference to some older media, but couldn’t find anything.
• Kamitani mentioned that 2188 Dr. Morimura, Nurse Morimura, Fuyusaka, and little Chihiro represent the four stages in a woman’s life.
• How Fuyusaka never recognized Shinonome or Sekigahara in hers dreams? Or maybe she did it unconsciously...?
• Morimura blood seems share the same taste for men: Izumis, Sekigahara and Hijiyamas look alike in terms of vibe. Which explains why Fuyusaka never cared for Kurabe, this one is the opposite of them...poor kid.
• Ryoko’s line to her little brother in Sector 3, “Don’t make fun of me”, became a meme among some japanese fan groups. If you search “馬鹿にするな！” on YouTube, you’ll find the scene. Some people seems to find her funny.
• Certain elements of the romance between Fuyusaka and Sekigara are based on a manga called "Tokimeki Tonight"(1982), in this manga the male lead is aspiring to become a professional boxing player. I'm not that familiar with shoujo, but the bike scene could be a reference to "Mars" (1996), a classic shoujo. It was one of the most popular manga to feature a bike scene emphasizing the city at night. Later, some other manga recreated the scene as a homage.
• There was supposed to have a love triangle between Sekigahara, Shinonome and Fuyusaka, but that was discarded due to schedule and budget issues. In japanese, Sekigahara calls Shinonome by four ways (Ryoko-san, Ryoko-senpai, Ryoko-nee and Ryoko) because the lines were already recorded before the changes, which makes him a little weird. Only calling her by her first name can come across romantic (like how he does with Fuyusaka in destruction mode), hence some people think he likes her.
• Fuyusaka's route and the dreams plot, as well as, the game's overall story are based on "Please Save My Earth" (1986), a sci-fi philosophical shoujo manga. Here is a synopsis I stole from Wikipedia "It is about six young people and a seven-year-old boy who share common dreams about their past lives as alien scientists who observed the Earth from the Moon."
• Sekigahara's route seems mostly inspired by the film "Total Recall" (1990).
• His story is also inspired by "Solaris," originally a 1961 science fiction novel by Stanisław Lem. It has two adaptations: the 1972 film directed by Andrei Tarkovsky and the 2002 film directed by Steven Soderbergh. I've only watched Tarkovsky's, but I don't know which one the writer got inspired by. I will pretend it is Tarkovsky's because, as far as I know, it is the most popular. However, I struggled to find where the references were.

  (Spoilers) In the movie, the planet Solaris seems to be able to use memories to recreate deceased loved ones. The protagonist’s deceased wife reappears before him and leaves him confused even if he knows she isn't real, creating a quiet, warm, dreamy, and unsettling atmosphere. My guess is that Kamitani tried to recreate this feeling by having dead Morimura in the beginning and then Fuyusaka, a mysterious girl who looks like her, alive and friendly to Sekigahara, who has no memories of her. Both routes seem to portray the love interests as mysterious or suspicious, with an eerie and dreamlike atmosphere if I think about this.

  My other guesses are that Solaris can be interpreted as a story about love, guilt, and memories and how people are trapped by them. Similarly, Sekigahara's route centers on a boy who was once trapped in the past, filled with guilt and struggling with love, with memories serving as a central theme too. However, unlike Solaris, Sekigahara overcomes it and ultimately embraces reality, a closure similar to Total Recall's messages. Another possibility is that George Kamitani aimed to recreate the storytelling style of Andrei Tarkovsky, where the narrative prioritizes themes and messages, adopting a philosophical, poetic, and ambiguous tone. To me, Sekigahara’s story, as well as Fuyusaka’s, are somewhat symbolic and open to interpretation. This is what makes the comparison difficult since it’s hard to define exactly what Kamitani may have interpreted from Solaris.

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Source: Developers Talks in "13 Sentinels: Aegis Rim Official Script Double Strand", this interview and this one too. For the timeline I used my own calculations and this table. Inspired by this blog.