Iryou-kei is when the band dressed up like doctors, iryou meaning "medical." Ikare-kei I've only seen used to describe something Yuuga was in, ikare meaning something along the lines of "to piss someone off." I've heard of other bands making up a name for their style before, especially if they felt they don't fit into the umbrella terms. Whether the names stick well enough to be passed onto the Western fan base is another thing.
Just to answer to one of the old shouts. Le_newtype: Afaik, they had Kisaki as their support bassist in the last live of Eternal. That's all I know. XD And some random support drummer I dunno anything about.