A love for fish that is deeper than the ocean. The film is based on an autobiography written by a celebrity marine biologist known as Sakana-kun. Everyone in Japan, both young and old, know him; a mild-mannered and humorous man with an unchallenged knowledge of fish. The movie follows Meebo, Sakana-kun's fictional counterpart, for whom life is all about fish and nothing else. Meebo single-mindedly goes after this passion, no matter what the obstacle!