Due to a fundamental lack of physical compatibility, Minami has been repeatedly dumped by boyfriends who find no pleasure in being with her. This insecurity leads her to accept an unusual offer from a stranger named Nishino, a handsome Tokyo University graduate with a PhD in science. His lifelong research theme is none other than female pleasure.

As a researcher, Nishino proposes to solve Minami's complex through direct, methodical development. He approaches intimacy not as romance but as a scientific investigation, cataloging her responses with clinical precision. The story follows their relationship, which begins as a purely experimental arrangement but grows increasingly complicated as personal feelings begin to blur the lines between test subject and lover.

The main characters are Minami, a woman whose low self-esteem regarding her own body makes her vulnerable yet curious, and Nishino, an enigmatic and stoic scientist whose poker face makes his true intentions impossible to read. Other key figures include Higashiyama, a rival love interest who enters the dynamic later, and Nakazato, whose presence adds further relational tension.

The setting is contemporary Japan, depicted through the contrast of everyday social spaces like cafes and bars against the private, controlled environment of Nishino's "laboratory" where the research takes place.

The narrative unfolds through several arcs. The story opens with the initial contract, where Minami agrees to be a test subject for Nishino to teach her body how to experience pleasure for the first time. This leads to a development arc where Minami learns to respond physically under his guidance, becoming accustomed to his unique methods, which differ entirely from her past experiences. A major turning point occurs when Higashiyama enters the picture. After a drunken mistake where Minami mistakes him for Nishino, she becomes physically entangled with Higashiyama, creating a love triangle that forces all parties to confront their feelings. Later volumes explore the psychological depth of the characters, particularly delving into Nishino's past and the "strong experience" from his youth that led him to declare he will never fall in love. The tension escalates further when characters begin contemplating scenarios involving more complex dynamics, including a three-way relationship, pushing the boundaries of both the research and their emotional connections.