After being used as a fake boyfriend to help Hayase fend off her ex, Takabe is shocked when she proposes a casual sexual relationship. The two begin meeting secretly in the school's nurse's office, leading Takabe to lose his virginity. However, his secret life becomes more complicated when he discovers Hayase's hidden habits and finds himself entangled in a provocative encounter with the school nurse, Taeko.
Takabe and Hayase continue their casual arrangement, but Takabe begins to develop genuine feelings for Hayase after they share a rare date outside of school. Their dynamic is complicated when another girl attempts to manipulate them, leading to a jealous confrontation and a wild group encounter. Despite the intimacy, Hayase clarifies that she only views Takabe as a sex friend, leaving him to grapple with his growing affection.