USApyon is a rabbit-like yo-kai from the moon, distinguished by technological expertise and a rabbit-themed aesthetic. His lunar origins manifest through advanced equipment including the interdimensional-travel U-Space and combat-oriented U-Bolts.

In *Yo-kai Watch: Enma Daioh to Itsutsu no Monogatari da Nyan!*, USApyon stars in the fourth episode "USApyon's Merry Christmas." Appointed as Santa Claus by the Yo-kai Committee, he partners with Hailey Anne Thomas to deliver gifts. Their mission shifts when encountering a child who refuses material presents and requests a cure for his hospitalized mother, emphasizing USApyon's role in human-yo-kai dynamics and empathetic response during duty.

The film's fifth episode, "Let's Go to the Yo-kai World," integrates USApyon into the central conflict. He allies with Nate, Hailey, Whisper, Jibanyan, Komasan, and Hovernyan against Zazel, who imprisoned Lord Enma and aims to sever human-yo-kai bonds. USApyon directly confronts Zazel's servants Aristokat and Duke Doggy in the battle to restore interworld balance.

During this confrontation, USApyon uniquely activates "Emperor Mode"—a powered-up state absent from other anime media—showcasing heightened combat capabilities in critical sequences.

Beyond the film, USApyon leads the Moon Rabbit Crew in the *Yo-kai Watch Blasters* video game expansion *Getto-gumi* (December 2015). This segment incorporates film-derived narrative elements, characters like Fuu 2 and Enma Daioh, and missions directly linked to the movie's events.