Hotaru no Hoshi

A young teacher has some good ideas about teaching, but he finds himself up against Japan's regimented and conservative school system. As a class project he decides to raise fireflies. Through the project his students become united and end up cleaning up a local river so the fireflies will have a home.
(Source: CrunchyRoll)
~~ Adapted from the novel “Hotaru no Hoshi” by Satoshi Muneda. ~~ Based on a real story.