Mizuhara Reito is an ordinary boy who wakes up in a world of 5 billion women and 5 men. Now it's up to him to repopulate the human species. Can he stay loyal to his missing childhood friend when all humankind is counting 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 was artificially created.

A bullied teenage boy wakes up in the future after going into cold sleep. His new high school is filled with nothing but girls, and more than a few of them seem to have an interest in him, especially his old teacher.

As Shouta adapts to his new life in the all-girls school, he starts to wonder why everyone is so eager to be friendly with him...

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 is secretly in contact with someone very important to him...

Reito finds clues leading to the origin of the MK virus. He also finds out that anybody who researches the origins of the virus tends to go missing quickly...

The rivalry between the girls at school heats up as they all strive to be the one to mate with Shouta.

As Shouta becomes accustomed to life as the only boy at school, he starts to seek out more and darker thrills. And his keepers are more than happy to oblige his every need...

As a messenger from UW's global headquarters arrives in Japan, Reito finds the secret behind the creation of the MK virus.

The Numbers come under attack from terrorists calling themselves Izanami. But one of Izanami's leaders is the girl Reito's been searching for since he woke up.