Sawako Yamanaka is the music teacher of the Sakuragaoka High School and one of its alumni. During her high school career, she was a member of the Light Music Club and founded the rockband Death Devil with her friends Norimi Kawaguchi, Della, and Jane, where she was a guitarist also the main vocalist of the band.

She eventually becomes the adviser of the two new generations of the Light Music Club under the leaderships of Ritsu Tainaka and Azusa Nakano, respectively. Additionally, she worked as the homeroom teacher of Class 3-2 during the senior year of the original four members of HTT.