Summer Days with Coo

is a 2007 Japanese animated film about a kappa and its impact on an ordinary suburban family, written for the screen and directed by Keiichi Hara based on two novels by Masao Kogure. Plot Following a dreadful encounter with a samurai, a young kappa's father is murdered. As he cries, the ground opens up and swallows him whole. 200 years later in modern-day Tokyo, Kōichi Uehara is peer pressured by his friends to pick on the quiet Sayoko Kikuchi, whom they continue to call ugly. Kōichi winds up in a muddy ditch where he finds a stone and within it, the kappa. He takes him home to his family who are awestruck at having a real kappa in their home. They name the kappa Coo, as he has forgotten his real name, and he quickly warms up to the family, though Kōichi's younger sister Hitomi has a strong disdain for him, but slowly she too accepts him. Their pet dog, Ossan, is revealed to be able to communicate with Coo via telepathy, though he tells him not to tell the Ueharas about it. Coo is spotted in the middle of the night by a couple and soon reports of a kappa sighting is spread throughout Japan. Wanting to know where he came from, Kōichi decides to take a holiday to the country with Coo to see if they can find any clues. They stay in a house where Coo communicates with a Zashiki-warashi (House Spirit Child) who informs him that he is most likely the last kappa as she has not seen anymore. Upon their return home, a couple of journalists ambush Kōichi and snap a picture of Coo. Journalists and photographers begin to camp around the Ueharas' house; practically leaving them no privacy. In an effort to appease them, Kōichi's father Yasuo takes a video of Coo to show to everyone and get various offers. Coo later learns from Ossan that he had a previous owner who loved him, but that one day he started getting beaten up by him due to the stress of school. He ran away before getting adopted by the Ueharas. Coo agrees to go on television with the Ueharas under the condition that Ossan come as well. On the talk show, they bring out a cryptid expert who resembles the samurai that killed Coo's father (possibly a descendant). He reveals that the samurai claimed the kappa's arm upon getting sliced off. Coo recognizes the arm as his father's and cries before psychically destroying the lights and cameras in the studio. He escapes the studio atop Ossan and flees with the arm with various bystanders in pursuit. During the chase, Ossan is hit by a car and dies.