Summer Days with Coo is an anime film that premiered in summer 2007, produced by Shin-Ei Animation.

About the production: the story comes from an original script, the film runs about 138 minutes and its current status is "finished".

Its main genres are adventure, comedy, drama and supernatural, with themes such as Youkai, Environmental, Coming of Age and Male Protagonist.

On AniList, Summer Days with Coo has an average score of 72%, a good score, and appears on 5,633 users' lists.

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" sleeping underground for the past 300 years, and names it "Coo". Koichi and Coo become good friends and starts living with his family. However, Coo could not adjust to the life style in Tokyo and starts to miss his family. On a hot summer day, Koichi and Coo decide to go on an adventurous road trip to find his peers. (Source: AniDB)

Official synopsis from AniList.