Completely changes their gender... They are originally born male, but under the curse the last demon king made the humans cannot birth anymore females so the Elves gave the humans a way to have children, by losing in a fight or by offering up their "Elven Ball" to the opponent (because even beastmen... can join this jebus) and they go from Male to Female until they get their ball back. If their ball becomes lost or vanishes they'll remain female for good and not be able to birth children.
Honestly... I just couldn't with the story anymore it was killing me... I got to chapter 9 and at the end was like "Nope, I'm done I cannot do this anymore!"
It had potential, but the characters f*cked it.
I haven't read this. But have to ask. What happens if a guy only looses one of his balls? Does he become a dickgirl?