damn, I was gonna recommend AKB48 but you don't like cutesey songs u_u
well I know SPEED is an older j-pop group but I haven't given them a listen (this thread actually mad e me remember them again). If you want a jrock band, there's Exist Trace which is all female although only one vocalist most of the time.
Check Alan out, she is amazing.
EDIT: I see you want groups instead of solo.
I still say try Alan out, you might end up liking her. smile
Yousei Teikoku as well. Their a rock band with a female lead singer.
I don't really know any GROUPS that have that new age-y sound that Kalafina has because girl-groups in Japan are predicated on the idea of being "kawaii", so you'll be hard-pressed to find things outside of that. But I think that groups from 1970s/1980s Japan were a bit more sophisticated sounding and less sugary and nauseating than their contemporaries (ex: Candies, The Peanuts, Pink Lady). However, I do know groups and bands that have a female lead backed by male musicians. When you put a group of females together, it's usually always an idol group nowadays. I want to suggest ALI PROJECT or OOIOO, but those voices aren't exactly mature-sounding, are they?
I do like Zone, though. They have a mature sound.
P.S. Soloist Akiko Shikata makes Kalafina sound like AKB48, if you want to check her out. But if you're honestly looking for that mature feminine sound, it's easier to find a soloist or a male-dominated band fronted by a female.