Well, to sum it up without getting too dark and AWFUL, he's a 12 year old amnesic cat boy who has a neglecting father and an emotionally, mentally, and physically abusive mother. He's trying to avoid a whole secret society trying to murder his brother (who is a straight up murdering sociopath but Ritsuka sort of worships him). He found out that he's supposed to be a part of this whole underground society that has just generally horribly violent people in it (same people trying to murder his brother). So... yeah, that's it. And he's in a weird not-relationship with a 21 year old man who has a habit of kissing him a lot.

He has a permission/opt-out post for this very reason.