A small, lone Kappa miraculously survives over 200 years into modern day Japan, when he is found by young Koichi. Coo, who is secretly adopted by Koichi's family, searches with his new human friend for unpopulated places in hopes of finding any remaining of his kind.
You can now watch Summer Days with Coo online on the following streaming providers in the United States.
| Writing | Masao Kogure | Story |
| Production | Yoshihiro Iwasaki | Producer |
| Sound | Kei Wakakusa | Original Music Composer |
| Directing | Keiichi Hara | Director |
| Writing | Yuichi Watanabe | Story |
| Writing | Keiichi Hara | Screenplay |
| Production | Yutaka Sugiyama | Producer |
| Visual Effects | Toshihiko Masuda | Key Animation |
| Visual Effects | Tomohisa Shimoyama | Key Animation |
| Visual Effects | Masaru Ooshiro | Key Animation |
| Visual Effects | Masako Matsumoto | Key Animation |
| Visual Effects | Chizuru Miyawaki | Key Animation |
| Visual Effects | Etsuko Sumimoto | Key Animation |
| Visual Effects | Jun Uemura | Key Animation |
| Visual Effects | Junichiro Taniguchi | Key Animation |
| Visual Effects | Masahiro Sato | Key Animation |
| Visual Effects | Tomoaki Chishima | Key Animation |
| Visual Effects | Toshiaki Iino | Key Animation |
| Visual Effects | Masakazu Ishikawa | Key Animation |
| Visual Effects | Yoko Sato | Key Animation |
| Visual Effects | Tomotaka Shibayama | Key Animation |
| Visual Effects | Masahiro Shigemoto | Key Animation |
| Visual Effects | Takaharu Ookuma | Key Animation |
| Visual Effects | Yoshio Chatani | Key Animation |
| Visual Effects | Ryotaro Makihara | Key Animation |
| Visual Effects | Nobuto Akada | Key Animation |
| Visual Effects | Masahiko Matsuyama | Key Animation |
| Visual Effects | Shinji Abe | Key Animation |
| Visual Effects | Takayuki Uragami | Key Animation |
| Visual Effects | Tetsuro Kaku | Key Animation |
| Visual Effects | Yuriko Ishii | Key Animation |
| Visual Effects | Kayoko Nabeta | Key Animation |
| Visual Effects | Kanami Sekiguchi | Key Animation |
| Visual Effects | Hideo Harigaya | Key Animation |
| Visual Effects | Kohei Yanagida | Key Animation |
| Visual Effects | Tetsuo Hirakawa | Key Animation |
| Visual Effects | Tetsuya Hasegawa | Key Animation |
| Visual Effects | Shizuka Hayashi | Key Animation |
| Visual Effects | Masami Otsuka | Key Animation |
| Visual Effects | Yuichiro Sueyoshi | Key Animation |
