Trying to find a manga (yaoi)

So unfortunately I only remember bits and pieces of this manga, but it's been driving me insane trying to find it. Okay so from what I remember the uke (light hair and glasses) is a teacher/ professor who in his free time engages in a sub/master relationship. The uke doesn't know the identity of his master because his master wears a white mask that covers all but the lower half of his face. I remember the seme was super attractive and had maybe shoulder length black hair and light eyes. Anyway SPOILERS the seme eventually shows his face and it turns out he's the uke's student. This probably describes the plot to a few hundred yaoi mangas, I know, but that's all I can recall. Any help is appreciated.