Mutsumi Shigino is a first-year high school student at Seiou Academy who serves as the secretary of the student council. She is physically small in stature, with light gray hair styled into short twintails and red eyes. As secretary, she takes on the role of tightening the often loose and relaxed atmosphere that tends to form under the student council president, Kanata Tento. Despite her harsh and blunt manner of speaking, Shigino is a diligent hard worker who willingly helps everyone with their tasks. She presents a firm and serious exterior, but this is undercut by a hidden childish side that occasionally surfaces. Along with fellow council member Noriko Kiryu, she is regarded as one of the voices of reason and conscience within the student council, acting as a model student who keeps the group focused. Her primary motivation appears to be a sense of responsibility and a desire to maintain order and efficiency in the council's activities. Shigino's role in the story is largely that of a supporting character, anchoring the student council's day-to-day operations and providing a grounded counterbalance to the more carefree attitudes of other members. While detailed character development is limited within the series, her interactions highlight her dedication to her duties and her sometimes contradictory blend of sternness and endearing immaturity. She does not possess any supernatural abilities, but her notable traits include organizational skill, a strong work ethic, and the ability to manage a chaotic environment through sheer persistence.