weia-yo :
Can Chiyo change her biological sex? Is that possible for any kitsune?
Reponse:
At this point she can’t even change her hair color so adding and removing essential ‘parts’ isn’t an option for her. A powerful kitsune could appear as any age or gender, though I don’t think they’re capable of reproducing that way (like a male kitsune can’t take on a female form and have a baby).
De jisuk - Source 18nov.2013