Shiki Yoshioka is the heroine of the story. Bearing dishonor,she despairs over the death of her father, who was a doctor. She entered the academy to avenge her father and bring down the chairman but she couldn't do it alone. Asking for the help of the quartet: Haru, Natsu, Fuyu and Aki, will she be able to walk her way into their hearts and fulfill her revenge?
In the beginning of the story, she is dressed up in the academy's boy's uniform. She also has short platinum-blonde hair, cut to make her look like a boy. She is also flat-chested, which adds to her appearance as a boy. In later chapters, we see flashbacks of her life with her father. There, her hair had not been cut and she had long blonde hair.