Muhi is a supporting character in the anime Punch Line. He appears as a small, white teddy bear who serves as the mascot of the series. Despite his cute and cuddly appearance, Muhi is an intelligent and powerful being with a deep understanding of the supernatural forces at work in the world of Punch Line. He was originally designated as W, a project by the antagonistic organization Qmay aimed at creating enhanced regenerative abilities. This experiment succeeded; Muhi can heal from severe injuries that would be fatal to ordinary creatures within minutes. After escaping a car accident, he was found and adopted by the character Ito Hikiotani, becoming a member of the Korai House household.

Muhi is a shapeshifter, able to change his size and form at will. He can manipulate the energy around him to produce powerful attacks and special abilities. He is also a master strategist, often staying several steps ahead of his opponents. His primary role in the story is as a guide and mentor to the protagonist, Yuuta Iridatsu, whose spirit becomes separated from his body following a cosmic event. Muhi assists Yuuta and the other residents of Korai House in their efforts to thwart Qmay's plans to use cosmic power to control the world.

Muhi possesses a serious and determined demeanor, but also shows a playful side. He frequently teases Yuuta and his friends in an affectionate manner. He demonstrates a strong sense of empathy and compassion, always willing to offer help and support to those in need. His loyalty is particularly evident in his relationship with Ito, who cares for him, and in his commitment to protecting the group from danger. Over the course of the series, Muhi proves to be not only a source of comic relief but also a key figure in the strategic battles against Qmay, using his regeneration and shape‑shifting abilities to turn the tide in critical moments. His development reinforces the themes of teamwork and sacrifice that run through Punch Line.