Kouichi Uehara is a fourth grade student living in the suburb of Tokyo. One day, he picks up a large stone which turns out to be a fossil of a baby "Kappa" who has been sleeping underground for the past 300 years, and names it "Coo." They become good friends and Coo starts living with Kouichi's family. However, Coo has a hard time adjusting to life among humans and misses his kind.

Daisuke Higashida is a serious first-year student at Higashizaka High School. He lives a peaceful everyday life even though he is not satisfied with the family who doesn't laugh at all and makes him tired. However, his father's company goes bankrupt one day, and he can no longer afford allowances, cellphone bills, and commuter tickets. When his father orders him to take up a part-time job, Daisuke decides to work at a nearby family restaurant in order to avoid traveling 15 kilometers to school by bicycle.

A compilation film of the Ansatsu Kyoushitsu TV series, featuring anime-only epilogue scenes not originally in the manga.

The summer of a man's boyhood memories continue. Still on the cusp between childhood and being a man, he has linked with the ghost of a young woman from the World War 2 era. She, and the ghosts of other young ladies from that time, continue adventures alongside their linked partners, learning more about each other and travelling through time via their supernatural connection. While he struggles to see his crush on her come to fruition, meanwhile his friend—a girl his age, pretending to be a boy—seeks his attention as well. (Source: ANN)