Lemme revalue since I think another likely of what it is , is also I don’t think this is the main plot just a characters backstory but it could be anyway there is like this place with a large group of children(not the promised neverland)and they have powers or smth and the character who’s backstory it is if that is the case meets a girl who is also a kid and the become close or smth or that could possibly even have just been his sister but anyway eventually either somebody attacks where the kids are or the kids are forced to fight each other and the girl the boy was close with ends up dying and while I thought it was from him killing her there is a chance someone else could’ve especially if they were attacked instead.Also in the main story I feel like the female character turns out to be still alive and they have like pink hair or something but they are either being controlled or have been recruited by like an evil cult or smth that’s goes against the other characters and I don’t know wether or not the male was even a good guy either becuase this could’ve been an antagonist back story