庭師・優太と妻・ひかりは勤め先である資産家夫妻から「夫婦交換」の誘いを受ける。EDに悩む優太だったが、他人に抱かれ淫らに乱れる愛妻を目の当たりにした瞬間、猛烈な勃起に見舞われる。インモラルな快楽に目覚めた二人は格差と羞恥が入り混じる四人交尾の泥沼へと沈んでいく

Gardener Yuta and his wife Hikari receive an invitation to "wife swapping" from the wealthy couple who work there. Yuta, who suffers from erectile dysfunction, is overcome with a powerful erection the moment he witnesses his beloved wife being embraced and wildly violated by another man. Awakened to immoral pleasure, the two sink into a quagmire of four-way sex, a mix of inequality and shame.