The character's name is primarily documented as Mouyuu, with Mouya noted as an alternate spelling in one context. Mouyuu serves as the second leader of Nanban High School alongside her sister Moukaku, forming a leadership duo. She is characterized as the more level-headed and honorable counterpart to her sister. Initially, Mouyuu seeks to kill Gentoku Ryuubi as part of Nanban's objectives. Her story involves significant confrontations with Shiryuu Chou-un. During their first encounter, Mouyuu retreats after Chou-un matches her strength despite being unclothed. In a subsequent battle, Chou-un decisively overpowers Mouyuu, leading Mouyuu to attempt suicide. This act is interrupted by a surge of Ryuubi's fluctuating power, which physically intervenes and compels Mouyuu to reassess her views on ruling the Kanto region. Following this ideological shift, Mouyuu changes allegiance and aids Seito Academy in destroying Kentei's lair within Nanban High School. This action contributes to halting Kentei's full revival. Her character arc concludes with this final documented action.