
Exactly what I tought. Well not the part of the delinquent but I also think that Yamamoto shaved himself to get closer with Todo. It's like in the end it explains that he knew of Todo's problem before they actually became friends and so he took advantage of the situation and pretended to have a similar issue so Todo would trust him.
But I don't think he actually wanted to rape him, I think he just snnaped. I mean he was just trying to make Todo fall in love with him but coludn't take it any longer . And I like this psycho plan of his, it kind of shows how much he loves Todo. ╮( ̄▽ ̄)╭

i was about to write the same thing and saw your comment

I do agree with you that Yamamoto is a twisted person,intentional or not, he did raped Todo. Though I don't think that the delinquent was an accomplice of Yamamoto, if so he wouldn't clicked his tongue like that after fighting with Todo. I think the delinquent either in love with Todo and got jealous of Yamamoto, or he could in love with Yamamoto, he did said their houses were close, childhood friends kind-of story. Personally I kinda like the ending, it left you with space to have your own kind of conclusion.
I think Yamamoto twisted person. He know that todo's friends knows all along about him having a small penis problem, so he shaved his hair crotch just to get close to todo with the perfect timing. And all the practice treatment its a lie just to get Todo used to it until he can rape him and make his own. And i think the delinquent is accomplice of yamamoto to get his plan work.#-.-)