Yonezu is a student who attends school and is in a relationship with Hina Takigawa, a student from a nearby all-girls school. The couple often meets after school to do homework and study together. They also use opportunities when Yonezu's parents are not home to engage in physical intimacy.

Yonezu secretly follows Hina and discovers her habit of performing solitary sexual acts in a public park, a secret he had known about for approximately six months without her knowledge. After witnessing her behavior, he confronts her about her exhibitionist fetish. This confrontation initially causes Hina to feel humiliated.

Following this discovery, Yonezu decides to move their relationship beyond conventional sex. He suggests they engage in public sexual activities together to enhance their sex life, accepting the associated risks for the excitement it provides. This marks a shift in their relationship as they begin to mutually explore her fetish.

Subsequent development shows Yonezu's actions becoming more forceful. He begins to think of new ways to fulfill his girlfriend's sexual needs and seeks to explore deeper levels of erotic activity. This leads to situations where Yonezu forces Hina to participate in acts against her will, taking their activities too far for her comfort.