Hina Takigawa presents a facade of purity and normalcy as a student at a locally famous all-girls school. Privately, she hides a potent secret: an intense arousal sparked by the risk of discovery during intimate acts. This exhibitionist drive compels her to frequent a secluded park area to urinate and masturbate, fueled by the thrill of potential exposure.

Her concealed activities are discovered by her boyfriend, Yonezu, who secretly observes her. This revelation leads to a confrontation where Yonezu expresses dissatisfaction with their conventional sexual relationship and proposes integrating her fetish. Consequently, she transitions from solitary acts to consensual public sex with him, embracing the shared risk and excitement.

In the sequel, their dynamic shifts significantly. Yonezu escalates their activities by introducing sex toys like vibrators and dildos, pressuring her beyond her established boundaries into acts such as urination in riskier locations near residential zones. This coercion triggers a negative trajectory, marked by her discomfort and a distinct loss of mutual agency in their sexual exploration, highlighting a regression in their connection away from earlier consensual experimentation.