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?
but the fact that you're still alive 
even in the outside world is proof.
no hay mayor evidencia de ello
que usted siga vivo.
no hay mayor prueba de ello
que el que usted siga vivo.
ma il fatto che lei sia ancora vivo,
pur trovandosi nel mondo esterno, ne è la prova.
mas o fato de você ainda estar vivo,
mesmo no mundo exterior, é uma prova.