Comment by 247 on Tre

@Tre helped raise a bunch of kids, one of them encountered a demon and snitched on the others to the demon to stay alive. Demon ended up killing all the kids except one, Gyomei ended up killing the demon, when people came to the scene of the crime and asked the girl what happened she said gyomei did it. They were gonna execute him but Ubuyashiki stepped in and he's been a demon slayer ever since. (That's what I remember reading, it might not be 100% accurate)