After a solar storm destroys the Y chromosome, the male sex dies out. But the women find a way to cross ova each other to survive. But after almost 2000 years, a boy is suddenly born: Hime. Hidden, he grows up and wants nothing more than to be a normal girl and his great love Kou to tell the truth. However, the chromosome decay seems to spread to the female sex. Researchers are working hard on a path back to give birth to men. Can frozen sperm be the solution?