Satou Matsuzaka is a lovely high school student with a reputation for being open to males. However, a chance meeting with a young girl called Shio Koube leads Satou to understand that this is her first and only true love. Satou, who claims to reside with her aunt, secretly shares an apartment with Shio. Despite her innocent look, Satou is prepared to go to any length to protect her lover, even if it means resorting to drastic tactics to keep their "happy sugar life" intact.