Tsubaki Yoshino is a second-year student in Class 2-A at Tsugumi High School, sharing the class with Riku Aoba and Sayuri Amamiya. She is an honor student academically. Her social circle consists of her close friends Sayuri Amamiya, Ayame Shīna, Yūka Fujikawa, and Sakura Shinjō. Ayame plays volleyball and Sakura belongs to the swimming team, showing Tsubaki's connections extend across different school clubs. Tsubaki wears glasses. Her role is part of the supporting cast surrounding Sayuri Amamiya.