Responses
The difference is that Kyouhei actually likes Takara romantically. It's a yaoi trope this "looks like I'm being abused but I actually like it I just can't tell right now that I've fallen in love" thing. It's confusing, I know, but it can be told apart from the actual rape scenes with a little yaoi experience, you'll see.
It's something related to their country, where you "can't" say you like it freely because is embarrassing, even more because it is homosexual. When you see one putting a serious, physical fight against the other, then that's rape.
I believe there's no difference between Takara and Yuuta-niisan.they are both abusers in my book.
p.s. please don't @ me, rape apologists.