Mio is a shy girl in the light music club who plays a left-handed, 3-Color Sunburst Fender Jazz Bass with an attached pickguard made out of tortoiseshell. She originally intended to join the literary club, but was forced into the light music club by her childhood friend and the club's drummer, Ritsu. She gets excellent grades in school, but is bad with listening to stories involving painful experiences, and cowers whenever something gross is brought up. While she can be mature and strict sometimes, she gets embarrased easily, and is often subject to teasing from Ritsu and Sawako, their club adviser. She cites that she chose bass since it is not the center of attention in the band, unlike the guitarist, though being the main vocalist somewhat negates this. Mio is more technical when it comes to music, and Yui often comes to her when she is in need of more guitar tutorials. She is the main vocalist in the group and also writes the songs, although they feature some odd lyrics like ''Light and Fluffy Time''. She is left-handed and is fascinated by other left-handed bass guitar players. Due to an unexpected accident in one of their live performances, and fan club for her is then formed, much to her dismay considering the circumstances surrounding it, whose founding member is the former student council president, who also stalks Mio.