From acclaimed director Keiichi Hara (Miss Hokusai, Colorful ), one of Japan's leading animation talents, comes a heartwarming summer adventure. One day, Koichi Uehara, a fourth-grader living in the suburbs of Tokyo, picks up a fossil that looks like a large stone while on his way home from school. To his surprise, he has picked up a baby Kappa (a Japanese mythical water creature), who has been asleep underground for the past 300 years. Koichi names this baby creature "Coo" and brings him to live with his family, and soon the two are inseparable friends. However, trouble abounds as Coo struggles to adjust to modern life, and begins to miss his family, leading Koichi and Coo to embark on a summer road trip adventure in search of other Kappa.