I think the manga is by Ike Reibun but I don't remember, I looked and didn't find it but the art reminded me of that persons work.

But the story goes like this -
This guy has a brother complex I think, and he loves his brother but his brother acts like he doesnt want to be around him, and his brother has this friend that is like really close to him and the other brother finds that annoying. So he trys to get in between them, only to find out that his brothers friend is not after his brother, but really him. And in the second chapter he drugs him with this cloth and rapes him. And his brother comes in and inturrups them but hes still drugged so his brother has sex with him and he doesnt remember it the next day, and then the friend mentions it.

Uhh, I hope thats clear enough.

Koiyami Archive?

yes thats it thank you*