Husband diagnosed with azoospermia—this single event changes everything. He makes an unexpected proposal: asking his wife, Kana, to bear a child with his younger brother. Initially repulsed, Kana gradually finds her heart stirred by her brother-in-law's relentless, beast-like advances that know no time or place. Bound by traditional morals, she slowly breaks free from the confines of wifely virtue, awakening to new emotions and desires. Her relationship with her brother-in-law transcends mere physicality, becoming for her the beginning of an entirely new life.