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?
If I... if I'm going to have a child, 
I want it to be with her!
Ich …
Y si voy a tener un hijo,
quiero que sea con ella.
Y si voy a tener un hijo,
quiero que sea con ella.
C’est…
Io... Se devo avere un figlio,
voglio averlo con lei!
Se eu... Se vou ter um filho,
quero que seja com ela!
Если... Если надо зачать
ребёнка, то пусть тогда с ней!