During the Obon holiday, Nanami visits her husband's family home. Her husband, Takaya, has been close friends since college with Tohru, who is now her father-in-law—and someone Nanami has always seen as kind and dependable. Ever since childhood, Tohru has been Nanami's secret admiration, and as she grew older, that admiration quietly transformed into romantic feelings. With Takaya delayed due to work, Nanami finds herself alone with Tohru. Unable to suppress her emotions any longer, she gives in to desire, crossing the boundary of their familial roles and passionately seducing him.