Reito Mizuhara, a researcher diagnosed with multiple sclerosis, must enter cryogenic sleep until a remedy for his illness is discovered. Running out of time, he musters the courage to express his feelings for his childhood crush, Erisa Tachibana. He bids farewell to his loved ones as his consciousness fades away. Suddenly, Erisa appears and pledges to wait patiently for him. After five years, Reito wakes up to a world affected by the "Man-Killer Virus," an epidemic that wiped out 99.9% of the male population four years earlier. Fortunately, his sclerosis therapy has given him and four other men immunity to the virus, turning them into valuable assets for humanity's repopulation. While other women vie for their attention and their genes, Reito stays true to Erisa and resists the temptation. Can he remain faithful to the love of his life despite the constant allure?