Aki Mizuguchi

Aki is a third year high school student and the bassist for the SS Girls. She is best friends with Yori and was one of the first people to encourage her to pursue Himari.

Yori and Aki are best friends. Aki sometime after they became friends fell in love with her, having wanted several times to take an "extra step" but decided to not confess her feelings and only stay by her side as a friend in fear of losing their current relationship.