Shinya and Mitsu are close friends who know everything about each other's love lives and sexual preferences, often joining their university friend group for drinking parties. Usually cheerful and assertive, Mitsu unexpectedly gets drunk early this time and ends up staying the night at Shinya's place. Their conversation grows lively as Mitsu opens up about accidentally having sex with someone from the group and feeling awkward about it. But as the truth gradually comes to light, their relationship takes an unexpected turn.