Bokura no Melancholy

Bokura no Melancholy summary:

Kanei Tomoya came back to his previous high school to be a substitute teacher in Physical Education. He met his fellow teachers on his first day and everything is sailing smoothly until Seta Kousuke came, his arts teacher back in high school. Everything became worse when he accidentally broke Seta-sensei's phone and was asked to be his lover in the span of his four months stay. Now will this "relationship" turn into something good or something bad?