Mochi is a fictional pet cat in Big Hero 6, belonging to Aunt Cass. He is a fluffy, often unimpressed-looking cat who appears in the Disney animated film and related series material. Mochi serves mainly as a comedic background character and a cozy part of Hiro’s home life, adding warmth and humor to the story. He is not a superhero or major plot-driving character, but he helps establish the everyday, family-centered side of the Big Hero 6 universe.