Definitely naming my character Ebony/Ivory. As for the rival, if we follow the gray speculation, his name could be Grayson or something. (Although I like Gilbert too coughPrussiacough)
For Homika, I was thinking Violet would be a suitable name. I dunno.
Shizui? should be called Triston. Kinda suits him.
Akumora is a nice name itself. Don't think a change is necessary for him.