User blog comment:Ein Inferno/Leaked Servants/@comment-27971189-20161231150419/@comment-27971189-20170130070154

Shuten is shape-shifter, Ibaraki as well. Its just they use their male form for combat while using their female form to trick people, seducing them, hence their male form got all the fame.

So can't really say they overdid the gender-bend for them. I myself kinda disappointed with Shuten and Ibaraki being loli as other fictional works I've read depicted their female form as 'femme fatale' kind of woman with superhuman strength (Personal taste issue ... LOL)

Quetzalcoatl is still male. Its just he is on same domain as Amaterasu, so having the actual male one summoned is impossible unless he hijack someone like Ishtar.