In a world where humanity faces extinction due to a mysterious virus, the survival of the human race hinges on the creation of hybrid offspring with demi-humans, beings with animalistic traits. The protagonist, a young man named Keisuke, is one of the few humans immune to the virus. He is recruited into a government program designed to pair immune humans with demi-humans to produce hybrid children who can inherit immunity and ensure the continuation of the species. Keisuke is assigned to live with a demi-human named Hina, a catgirl who is initially reserved and wary of humans due to past mistreatment.

As Keisuke and Hina navigate their forced cohabitation, their relationship evolves from one of necessity to genuine care and affection. The story explores their growing bond, as well as the challenges they face in a society where demi-humans are often marginalized and exploited. Keisuke’s interactions with other demi-humans in the program reveal the complexities of their existence, including their struggles for acceptance and the ethical dilemmas surrounding the government’s methods.

The narrative delves into themes of coexistence, prejudice, and the moral implications of using demi-humans as tools for human survival. Keisuke’s journey is marked by his efforts to protect Hina and other demi-humans from exploitation, while also grappling with his own role in the program. The story balances moments of lightheartedness and humor with darker, more introspective elements, creating a nuanced portrayal of a world on the brink of collapse.

Key characters include Keisuke, whose compassion and determination drive much of the plot; Hina, whose vulnerability and strength make her a compelling counterpart; and various other demi-humans and humans who represent different perspectives on the crisis. The series examines the tension between survival and morality, as well as the potential for connection and understanding across species boundaries. Through its exploration of these themes, the manga presents a thought-provoking narrative that challenges readers to consider the cost of survival and the meaning of humanity.