Giselle is a trans woman, not a boy, and that's practically canonical, just like in the case of Crona from Soul Eater, you should at least put "1 other".

Sorasake said in comment #2574889:

Giselle is a trans woman, not a boy, and that's practically canonical, just like in the case of Crona from Soul Eater, you should at least put "1 other".

Taken from the Danbooru Wiki page on Giselle:

Although Giselle is often referred to as a girl, he is a biological male (and should be tagged as such).