Looking for a manga

It's a very well drawn manga
About a male teacher who I think has depression
He's very dark and have crisis and breakdown easily (he's middle aged maybe like 40y/o)
A female student see that and try to help him by being by his side and comforting him (often at lunchtime)
(She also allow him to rest on her legs and talk with him like that)
The story focuses on these two
That's all I can remember