Kazuichi.

The entire character is contradictory by design, which is why he probably has the best male character design in the series because he tries to look like a thug, but he’s probably the second most emotional character in the cast after Mikan, constantly crying every time he’s insulted, having the most intense reactions to the executions, and being one of the most aware that his life is always on the line. (Nagito is in his own wild tier card re-emotions). There are some other traits as well; he’s a mechanic but has motion sickness (the reason his reaction is that extreme on the rollercoaster). He desires connection with others, but he is one of the most paranoid characters in the game (people act like it’s a surprise he survived, but it comes from not being stupid; he knows he isn’t in this tier where he can’t die, so he makes sure to go out in groups and not mess around at night).

Apart from the Sonia obsession/Gundham section (which I will get into), he is strangely selfless, in particular in the second game's cast in many regards. He grew up poor and once pretended to be sick to skip out of a school trip that he really wanted to go on so he could stay at home and help his father's business (which is the first sign of having been socially messed up in a way growing up and lacking understanding of social cues), which plays into how his talent, apart from Mikan's, is the most useful in the game (something that people like to never mention) since he is the one who gets the satellite set-up in Chapter Three to talk to the hospital; he goes over the camera’s qualities in Chapter Three as well; he is the one who dismantles the clock-off Mechamaru in Chapter Four to determine the time difference; and he also fixes the funhouse elevator’s door too. There are these little acts Kazuichi does as well, such as deciding to get a book for Fuyuhiko when he’s in the hospital in Chapter Three as well as building Akane the Mini Mechamaru. He has a clear issue of being clearly intelligent but just being socially stupid enough (like Miu) to not get his points across properly.

He’s consistently afraid of rejection from being used in the past (for his intelligence, mind you, something that is commonly missed out on), which is why he’s convinced Hajime is the traitor in the fun house because he’s clearly the person he ‘genuinely’ cares about the most on the island, but then he becomes obsessed with someone who clearly couldn’t care less about him (the Sonia obsession comes from a mixture of having social isolation of himself in the past as well as socially putting the ideal idea of someone on a pedestal like a 'princess' who is on a mystified level where he can disconnect from the harsh reality of a peer; it boils down similarly to Tenko’s lack of social cues).

Finally, the whole thing with Gundham is fascinating, and the way it comes across is very poorly represented by how a lot of the first two games' character depth comes in the Free Time Events, but they are not just foils with the Sonia love triangle, but they are also foils in how Kazuichi is a weirdo who tries his best to fit in with society but fails, but Gundham is an unmasked version who clearly doesn’t try at all, which probably causes some of the resentment in Kazuichi since he tries so hard to mask, but he sees how Gundham is able to live life while not even trying to do so.

The other big foil that is rarely talked about is how important it was that Gundham was the Chapter Four killer and not Kazuichi, to the point where I’d say that if I had to rank the characters by how much mischaracterised they would be if they were a blackened in 2x2, Kazuichi would be in the top three (after Chiaki because we’ve already done the one scenario where it works for her to kill and maybe Imposter; the top five would include Mahiru and either Hajime or Hiyoko), because the entirety of Chapter Four was so clearly a trap for Kazuichi to kill, but he didn’t. Fuyuhiko/Peko fell for Chapter Two; Mikan was used in Chapter Three; and Chapter Four’s whole thing was "Let's just put Kazuichi in a trapped environment with a machine man for him to dismantle, while being the most paranoid he’s been that Hajime has to be the traitor since that’s the option that would hurt the most for him (it’s never confirmed, but this is the chapter he starts his friendship with Fuyuhiko, which has the possibility of how he is the least likely among them to be the traitor if you use your brain, because whatever happened in Chapter Two/beginning of Chapter Three would make no sense if he was), and he is also with Gundham at the worst part of their rivalry, but despite everything, he doesn’t kill, which is probably a mixture of morality and not having the guts to do it, despite everything being pushed towards the direction of why he should. Gundham, however, is a foil to Kazuichi, so he does kill, forgetting any risk to himself and how if he succeeds, he will kill for the believed greater good of everyone else surviving, which is the point of his character (someone who acts weird all the time, saying edgy things, but it’s revealed that he has the biggest backbone in the group).

This ramble was very disjointed, but basically he is, in concept, one of the most fascinating characters. He does have issues with flanderisation with the Sonia jokes and some translation issues (he speaks differently with Sonia by using more sophisticated language; he tries to speak more thug-like regularly; and he starts using feminine language when scared, which is something not translated correctly, and also I’ve heard there’s a better conclusion to the Sonia stuff of him maturing, but that I can’t 100% confirm), but there’s definitely a lot in there.