"Eiga Oshiri Tantei Yume no Jumbo Sweet Potato Matsuri" is a feature-length anime film centered on the adventures of Oshiri Tantei, a detective with a unique appearance—his head resembles a human buttocks. The story unfolds in a whimsical world where Oshiri Tantei and his assistant, Brown, are called upon to solve a mystery involving a grand sweet potato festival. The festival, a highly anticipated event, is thrown into chaos when the prized jumbo sweet potatoes, essential for the celebration, go missing.

The narrative follows Oshiri Tantei as he investigates the disappearance, uncovering clues and encountering a variety of quirky characters along the way. The detective’s sharp intellect and unconventional methods are put to the test as he navigates through a series of comedic and puzzling situations. Brown, ever the loyal sidekick, provides support and comic relief, adding to the lighthearted tone of the story.

As the investigation progresses, Oshiri Tantei discovers that the theft of the sweet potatoes is tied to a larger scheme threatening the festival. The film builds toward a climactic resolution where the detective must outwit the culprits and restore order to the event. The story emphasizes themes of teamwork, problem-solving, and the importance of community, all wrapped in a humorous and family-friendly package. The characters’ interactions and the playful nature of the mystery make it an engaging watch for younger audiences, while the clever plot ensures broader appeal.