In the peaceful forest by the sea, the kind-hearted and curious young sea otter Bonobono lives a simple life with his father. One day, he and his closest friends, the anxious chipmunk Shimarisu-kun and the short-tempered raccoon Araiguma-kun, discover a mysterious tree known as the Kumomo. Local legends say this special tree holds an ancient secret and a magical connection to the forest's animal inhabitants.

Their discovery sparks a gentle adventure as the trio sets out to learn the truth about the Kumomo's past. The search leads them to encounter various other residents of the forest, including the sensible and strong Fishing Cat, the stoic badger Anaguma, and the wise but eccentric father of Kuzuri-kun the wolverine. As they work to solve the tree's riddle, a conflict begins to grow between different animal communities in the forest, threatening the harmony of their shared home.

This second theatrical Bonobono film, released in Japan on August 10, 2002, was produced entirely with 3D computer animation. Directed by Koki Kumagai and produced by Amuse Pictures, the movie has a runtime of 61 minutes. The story stays true to the gentle, philosophical, and gag-filled tone of Mikio Igarashi's long-running manga series, focusing on themes of friendship, empathy, and living in harmony with nature rather than on a complex villain-driven plot. While a specific, detailed narrative arc for this film is not well-documented, the core conflict revolves around the mystery of the Kumomo tree and the need to resolve the growing tensions between the different animal groups in the forest.