Kinu is a serious and studious high school girl who views relationships with a purely academic lens. She believes dating should happen in the library and that physical intimacy, like kissing, is something reserved for after marriage. Her worldview shatters when she accidentally walks into an empty research room and catches Haruka Mihara, the school's notoriously handsome playboy, in a compromising moment with another female student. Overcome with shock, her legs give out. This incident plants a new, obsessive thought in her mind. If she eventually wants to have children, she reasons she must overcome her aversion to the physical act of sex. Believing knowledge is the only way to conquer fear, she summons Mihara to an empty classroom the next day and makes an unexpected proposition: she wants him to be her teacher and guide her through the confusing world of physical intimacy, all in the name of preparation for a hypothetical future family.

The story unfolds within the charged atmosphere of their high school, a place where reputation and rumor travel fast. Haruka Mihara carries the reputation of a carefree womanizer, a label he seems to accept without much resistance. He agrees to Kinu's clinical proposal, intrigued by her unusual mix of naivety and intense resolve. What begins as a formal, almost contractual arrangement between a diligent student and her unconventional tutor quickly becomes more complex. As their secret meetings become more frequent, the rigid lines between teacher and pupil, or between a physical education and genuine emotion, begin to blur. Kinu starts to question if her feelings are purely academic, while Haruka reveals there might be more beneath his detached, flirtatious surface than anyone at school has ever bothered to see. The narrative follows their evolving relationship, exploring early moments of awkward negotiation to deeper emotional and physical discoveries. Their pact challenges their personal boundaries and forces them to confront what they truly want versus what they initially thought they desired.