Mao Amachi, frequently referred to as Mao-chan, is a six-year-old boy and a classmate of the protagonist Ashibe Ashiya in the series. He is a supporting character who regularly joins Ashibe, their friend Yuuma, and the seal pup Goma-chan on their everyday adventures. Mao-chan is visually distinctive, with black hair that is styled into a shape reminiscent of a capital M, including a clear M-shaped tuft at the center. His hair is cut to ear length. He is a member of Ashibe's peer group and participates in the slice-of-life activities that define the story. Information about his deeper personality, personal motivations, independent development arc, and any unique abilities is not extensively documented in available sources. His primary role is as a recurring companion within the main cast of children, contributing to the group dynamics rather than driving major plot developments. His key relationships are with Ashibe, Yuuma, and Goma-chan, as they frequently spend time together. No reliable direct information exists regarding his background, family situation, or any notable abilities beyond his participation in group activities.