Mizuhara Reito wakes up in a world of 5 billion women and 5 men, and it falls to him to repopulate the human species; he struggles to stay loyal to his childhood friend when all humankind counts on him to sleep with as many girls as possible.

As Reito begins to adapt to this new, man-less world, he finds clues that the virus had artificial origins.

A teenage boy wakes up in the future; he finds his new school is filled with nothing but women.

Shouta adapts to his new school life.

Reito goes to visit the widow of the very first victim of the MK Virus in Japan; the widow knows more than she should, and has secret communications with someone very important to him.

Reito finds clues leading to the origin of the MK virus; anyone who researches the origins of the virus go missing.