Sawako Yamanaka

Sawako is the adviser for the wind instrument club at Yui's school. An alumna of the school and a former member of the light music club, she does not want people to know she was formerly a member of a heavy metal band, thus she covers up by being mild and gentle to her co-workers and especially to students. She is forced to be the adviser of the light music club, as Ritsu blackmails her after the girls learn of her past, though it is unknown whether she stopped being the adviser for the wind instrument club as the story progresses. Though she has a mature and gentle demeanor in the school, Sawako, affectionately addressed as "Sawa-chan" by both Ritsu and Yui, displays a totally different, completely authentic character when she is alone with the light music club. In reality, she is a rather wild, lazy and quite an irresponsible teacher who enjoys dressing up the light music club in, sometimes embarrassing, cosplay costumes, much to the dislike of Mio. She names the club band ''After School Tea Time'' after the members take too long deciding on a name themselves, and to maintain the secrecy on her heavy-metal image. She once momentarily pitches in for Yui with her Gibson Flying V electric guitar. Sawako once owned a Gibson SG Standard guitar given by her dad's friend, but she kept it in the music room because she thought it was not in a playing condition anymore.

Her surname is taken from the pillows vocalist/guitarist Sawao Yamanaka.