Mio Okazaki and her brother Ichiro maintained a secret relationship, pretending to be a married couple. However, after their father's death, younger brother Jiro began secretly meeting with Mio whenever Ichiro was away on business. Filled with constant desire, Mio ignited an uncontrollable obsession in Jiro. Hidden lust and a deep emotional bond soon emerged between them, driving their forbidden relationship to even greater depths.