☆One day after school, Nao, a dark-haired gal looking to kill time, installs a diagnostic app and starts searching for a guy to test it on. Along the way, she bumps into Kyoko, the Discipline Committee Chair, and invites her to join them. Returning to the classroom, they find Ayato, a slightly perverted guy, waiting alone. After some back-and-forth, the three start the compatibility test. Their actions gradually escalate, leading them into sex.

...Unbeknownst to them, this was the effect of the Physical Compatibility Test.