Here's some more detail from the wiki page
Lumi is just a face, the actual music is done by:
Producers:
Tetsuya Mizuguchi
Kenji Tamai
Lead Singers for "Lumi":
Rachel Rhodes
Nami Miyahara
Also not the name for the singer "Lumi" = "Lumines"...
All his musical efforts are tailored for this games to begin with, so it isn't like one commodity is being used to market another commodity as they both are more or less the same. For the last decade or so Mizugichi has been working on the cognitive phenomenon of Synesthesia and all this is his emperical research.
The only thing left for him to do is publish a report, with a wide cross sectional sample of subjects and qualatitively measure the synesthetic sensations. He could win him self a PHD as well as get funding for all his projects from Nihon's Goverment.
The question here is why hasn't NPA (Nihon Psychological Association) or APA (America Psychological Association) picked up on his research?