The narrative centers on , a high school student who experiences her first love confession from a classmate. The story explores her reactions to this milestone and the subsequent complications involving her stepbrother, Takeshi, who has recently moved back home. Key themes and tags associated with the series include:
As the title "Kaihatsu Nikki" (Development Diary) suggests, the plot focuses on the character's sexual awakening and experiences.
The figure is based on Mucha's original illustrations and features "cast-off" clothing options, allowing for various display styles.