Yuto Arima is an approximately 11-year-old boy with brown hair swept mostly to the left, short spiky bangs, and navy blue eyes. His typical outfit includes a navy blue school uniform jacket, a collared shirt (noted as pink and blue in one source and white in another), a tidal blue necktie, beige pants, and black shoes. He wears the specialized Yo-kai Watch U-1 on his left wrist.

Yuto first appears in a school scene receiving a corrected test with an average score of 72 points, a result causing visible surprise among his classmates. Unaware his performance was influenced by a Yo-kai's possession, he later returns home. Upon entering his room, he hears an unidentified voice instructing him to "put it on." Discovering the Yo-kai Watch on his desk, Yuto presses its button after the voice repeats the instruction, revealing the Yo-kai Fuu 2.

Fuu 2, later revealed as the transformed human protagonist Nate following an accident, bonds with Yuto. Fuu 2 assists Yuto in pursuing his ambition to become a manga artist, providing guidance and encouragement.

One source also mentions Yuto joining a team led by "Sora," receiving marks from Agnes and Rachel Alucard, interacting with numerous characters across different franchises, and facing rivalry from "Yuto Ijika." These elements appear unrelated to his canonical depiction in the film *Yo-kai Watch: Enma Daiō to Itsutsu no Monogatari da Nyan!* and lack corroboration in other sources. Concrete information regarding Yuto Arima's appearances or development in other Yo-kai Watch media beyond this film debut is unavailable. Internal localization files for an unreleased game listed "Leo" as a potential localized name for him.