isn't mahito like six
Uh...no? Yes he was "born" relatively quickly but he's born from the hatred & distrust of other humans, which technically is like super old cause humans hate and don't trust each other since the beginning of time. He doesn't act like a child at all, he's very smart & works with Kenjaku during most of the events in the show. He just acts childish for fun. This isn't a situation where it's some anime girl who's 30000 years old but looks & acts like a child.