you mean the guy who lives under a school and mak girls sing to him? I only remember the part where he went like, "SING TO ME" "OOOOOOOOOO" "I SAIS SING TO MEEEE"
*cough cough* it was tragic
Took me forever, but this may be what you're after. God was in short trousers the last time I read this though, so no promises.
http://www.mangago.zone/read-manga/lovely_phantom/
OH MY GOD YES IT WAS THIS LMAO
Glad to be of help.
Who really liked phantom of the opera or something? But I think he was chemistry teacher and was really ugly. I think he also lived at the school? It was a really cheesy typical story but does anyone remember it?