"Eiga Sumikko Gurashi: Tsugihagi Kōjo no Fushigi na Ko" is a feature-length anime film based on the popular "Sumikko Gurashi" franchise, which centers on a group of endearing characters living together in a cozy, everyday setting. The story begins when the Sumikko characters—Shirokuma, a shy polar bear; Penguin, a penguin who questions his identity; Tonkatsu, a piece of pork cutlet with a small bone attached; Neko, a timid cat; and Tokage, a dinosaur who hides his true nature—discover a mysterious abandoned factory near their home. Intrigued by its secrets, they decide to explore it.

Inside the factory, the group encounters a strange, patchwork-like creature named Furoshiki, who appears to be made of various fabric scraps. Furoshiki reveals that the factory was once a place where forgotten and discarded items were repaired and given new life. However, the factory has fallen into disrepair, and Furoshiki is struggling to keep it running. The Sumikko characters, moved by Furoshiki's plight, decide to help restore the factory and uncover its hidden mysteries.

As they work together, the characters learn more about the factory's history and its connection to a magical world where forgotten objects and memories are preserved. Along the way, they face challenges that test their teamwork and individual insecurities. Shirokuma confronts his fear of the unknown, Penguin grapples with his identity, Tonkatsu learns to embrace his uniqueness, Neko finds courage, and Tokage begins to accept his true self. Their journey is filled with whimsical moments, heartfelt interactions, and a sense of wonder as they piece together the factory's past and its significance.

The narrative emphasizes themes of friendship, self-discovery, and the value of giving new purpose to things that have been overlooked. The film maintains a gentle, slice-of-life tone while incorporating elements of fantasy and adventure, making it accessible to both children and adults. The characters' growth and the factory's restoration serve as a metaphor for resilience and the importance of cherishing what others might discard. Through their efforts, the Sumikko characters not only revive the factory but also strengthen their bond and gain a deeper understanding of themselves and the world around them.