Just a few idas I'm working with:

Claire: Shadow people with that can mix spells, and live in what used to be Greece.

Yuki: Birdlike people with a culture of mask symbolism living in tribes spread across Asia. They can summon the spirits of legendary figures through ritualistic dances (working on this)

Miriam: Slimes that can only ingest things with no life, and live in the Polynesian islands and one separate island that acts as their capital.

How do these sound?