Okay this is very interesting mangá, and sad too... now spoiler for those who couldn't get who are the masked man, in order of speaking of the second chapter: the first one is the obvious guy with strong perfume, the second masked guy is the class rep that asked for help with the paper, and the last one, and the one who surprised me, is the teacher, judging by the pov of each speech. Their reasons are twisted and most probably left him broken, I really wish that there was a continuation.
Fukumen Danshi