Kazumi survives a near-future viral plague that transforms women into aggressive, sex-crazed predators, forcing him into constant conflict while seeking safety. He traverses this hazardous landscape with Tsugumi, his sister-in-law. Their relationship evolves beyond survival as mutual erotic urges emerge during their journey. Shared struggles against infected vixens and scarce safe havens intensify their bond, sparking intimate encounters despite ongoing threats. Kazumi prioritizes protecting himself and Tsugumi from the infected horde while navigating their growing attraction. His development focuses on adapting to apocalyptic conditions and managing their complex, consensual relationship amid chaos. The narrative concludes without resolving the pandemic or their ultimate fate, leaving survival uncertain.