can you guys help me find this yaoi manga?

So it's a student x teacher. If I remember correctly, the student had cigarettes in his bag and the teacher used this to blackmail the student. When he graduated, the student asked the teacher for his watch. Years later, they met again at a reunion. I remember the teacher tried to make a move on the student but he was rejected, and then he remembered that he never once saw the student smoke. That's all I remember.