Looking For Yaoi!

Hi guys! I’m looking for a yaoi. There’s a part where they’re both inside a train and are obviously turned on. The train is very crowded and the space is tight. After getting off at the next station, they go to the top’s apartment and have sex on the couch. I also believe the top’s brother was supposed to pay a visit shortly after. From what I can remember, they still had an afternoon class, but they ended up skipping it. Does anyone know the title?

Another scene I remember is when they were having sex near the front door. The top’s brother knocked because he was looking for him and thought he heard something inside. He kept knocking for a while, but eventually left. If I remember correctly, the brother had long black hair.