That's actually a really good point about Kento. The last time we saw him was when he was beaten and raped on the ground, and then he just kind of disappeared? Nobody thought about putting him under any kind of watch or custody, especially after his only parent was arrested? Seems a bit odd.
Also, really interesting parallelism with the cult of the children and the shamanic barbarism of the Jomon. Guess it's supposed to be a Lord of the Flies thing, but to be honest, would kids really do something like that, using all those big words and complex philosophies? When I was a kid, we'd all imagine ourselves in our own society with imagined roles or chasing down fantastical monsters, but I don't think it'd escalated to carving yourself up.