Saving My Stupid Youth (2014)

Heisuke teaches at his alma mater, an all-boy’s Buddhist high school and leads a very ordinary life, except for the fact that he is still tortured by the memory of an unfortunate incident that took place there involving him and his school 14 years ago. In hopes of closure, he strikes upon a plan to jointly hold this year’s Culture Festival with a nearby girl’s school, with which there are chilly relations. Determined at all costs to make the event a success, Heisuke finds himself dealing with a constant stream of problems along the way.

Source: TMDb