Not trustworthy enough to be a mod? Don't worry because there's still a thankless job waiting just for you!

A janitor is a sort of eunuch mod that can delete things… and that's all, really. They're not supposed to be able to ban people but they can clean up the clutter. To be completely honest, I'm not sure that there's a hierarchy like this in Japan. I think they may just have janitors and the actual admins are in charge of all things serious like bans (from what I can recall from the old school code, that kind of thing was handled server side and there weren't functions for it in the board scripts).