The kanji you're translating as group has a more military feel to it . . . like regiment or squad. Maybe party or company?

So, Female Regiment. Plus, while "of the Rainbow" is technically a correct translation, it sounds a bit awkward to me. In fact, the "Female Regiment" part sounds awkward in English as well, since we're never quite that specific (after all, no American straight boy would be caught dead in a group with the word rainbow in it

).
So, literal translation:
Rainbow Female Regiment Prism Knights.
But if I were licensing it, I would just call it Rainbow Prism Knights. Or Rainbow Prism Knights: Female Regiment. But then that sounds like there's a male regiment out there somewhere . . . and I have no idea if there is.
Now I'm curious if the little blondie is sweet and cute or a chibi-thing-that-kills.
