Oh! Thank you for completing the entire game, and also for your lengthy review. I can tell you were deeply invested in the story, which led to strong feelings of confusion and resistance. <3
From MC's perspective, it aligns with the player's impression—things happen without warning, extremely suddenly: the situation takes a sharp turn for the worse, why? Why did he do that?! After all that conversation between them, what was the point of everything they said? Is he insane? Why did the author write such a twist? Is the author insane?
I usually revise repeatedly before finalizing a draft, more times than anyone could imagine. I'm fully aware of the feelings players will have—some might understand the characters, others might feel frustrated.
But rather than stating everything explicitly, I prefer to leave things blank, to leave cracks, and enjoy the moments when players ponder, "Does something feel off here?" and a flash of insight strikes them. Like with mystery novels, I want to encourage players to piece together the clues, so that when they replay the game, they have an "Aha! I see now" moment. I find that very interesting.
MC is prevented from uncovering the truth—that's because Aoi simply doesn't want to reveal it. He chooses to stop himself from becoming an even more monstrous criminal, and still wishes to remain by MC's side as a "clean" person. He actively uses an extremely drastic method to "lock" their friendship and his own sins.
Aoi understands his own sociopathic nature. He doesn't dare take the gamble—he can't bet that his flaws will change just because he falls in love with MC.
What if he can't control his urges? What if he truly ends up inflicting physical or verbal violence on MC? Just like the line he says in the main story, "Are you willing to bet that he's a good person? Huh?" — isn't he also talking about himself?
He believes that, one day, he will inevitably commit some heinous atrocity. So before any of those problems arise, he forcibly cuts off the possibility.
For someone as arrogant, narcissistic, and paranoid as Aoi, accepting that he can't do anything, that he's become useless, accepting MC's and Higan's pity—and even having to swallow the jealousy and possessiveness that come with being a friend—is more infuriating than the pain of death. It's a long, drawn-out torture, a kind of cruel torture.
Aoi already foresaw this outcome, yet he still went through with it.
This is the third ending he chose for himself. Originally there were only two: one is death (the true ending, on the rooftop); the other is indulging his ever-expanding desires, committing increasingly severe misdeeds until death (the bad ending).
In the true ending, he does everything in his twisted, gentle way to protect MC. That's the "love" a bad person can give—even if this stubborn, hard-mouthed guy would never admit it.
He will quietly keep the secret, until he is burned to death by the flames of jealousy.
Higan's story is connected to my other games(his father was RO in that game), and I don’t want to reveal everything too early, haha. Extra Chapter 1 is a supplementary part from Aoi’s perspective in the true ending, which may answer some of the questions on your mind. Extra Chapter 2 is currently in production and will delve deeper into Higan’s character—stay tuned.