I don't believe he(Hoshino) thought or knew that Katou would rape Miwa when he left the library.
Given the situation how could he not have figured out what would transpire?
I think he thought he would say his goodbye and see that he belonged to Hoshino, I don't think he thought he would rape him.
I believe we have a difference in opinion. I believe like a lot of other commenters that he knew because it's common sense and given the severity of the situation and the angry disposition, would you not stick around to make sure everyone is alright?
Personally, I would have totally stuck around simply because he could have hit him, let alone the rape. I just thought he didn't think he would be raped.
Dude that's my point, but yeah I also think that he knew both their personalities so he should have stuck around and prevented the rape like anyone concerned for his love would do.
I agree. Hoshino looked pretty surprised when Katou was leaving the library. I don't think he was expecting Katou to rape Miwa.
Katou, Hoshino and Miwa are all jerks.
Hoshino knew they both were in love with each other yet he went after Miwa, being friends with Katou he knew he was reluctant to admit to liking Miwa which makes things even worse. Yet he is the only one who is redeemable from the three as he makes amends for all his actions. And even at the cost of his own happiness gets the other two together as they were meant to be. Yet I do admit leaving the guy you love to get raped by the guy he actually loves was a bit twisted.
Miwa after being rejected started to use Hoshino as a rebound and as a convenient outlet to make himself feel better. He never properly tries to understand any of the other two even though he is so close to them he only thinks about himself and plays the victim card a bit too much.
Katou has a bit of a sexuality crisis going on throughout the story, whilst the other two are accepting of their own he is not. He pretty much becomes the catalyst for most of the hurt and misunderstandings in the story. He rejects Miwa in a horribly misleading way and only after seeing Miwa and Hoshino developing a closer relationship does he start, out of jealousy, to accept his feelings. And then he rapes Miwa and leaves Hoshino to be the one putting the pieces of his failed relationship with Miwa together. He is also as selfish and self centered as Miwa as he never apologizes for anything and it's Hoshino and Miwa who eventually save him.