What kind of magic will it be based on? Will it be based around already existing 'magic' (e.g. Voodoo), or around defunct magic (e.g. Pagan, Zoroastrian) or is it just a case of picking up a magic wand and flicking it around? Shinto magic is based on cleansing, if you're wanting to keep with the Japanese theme. Maybe each character could excel at one type of magic more than another (if you were going for a mix that is)?

Other than that, I'm interested :)