Ambivalent ~Doutei wo Sutetara Shinu Sekai~ summary:
A new type of sexually transmitted disease spreads around the world. When infected, women's sexual desire increases by several dozen times, and 99% of men die. In a world where casual sex = death Sadao Shindo, who has no sexual experience, vows not to have relations with anyone until a vaccine is developed, but the temptations of women overwhelm him...!