I guess just like how humans have bad guy, that mean in Youkai World, there's a bad youkai too, even tho they lived side by side for a long time. Kinda fun if this happen in real life! Minus the void
I'm a bit disappointed we didn't see how the snake-tree conflict was resolved but maybe it might be a plot point later on? I'm really impressed by the amount of world-building we see here with both yokai students and teachers (Tsuchida sensei is really cool he reminds me of Kamajii from spirted away + a cat) in such a natural way.