One, Sakamoto of Animetal is a former member of JAM Project, though I suspect him to turn up in a reunion sometime as JAM Project plans to have a 9 member JAM Project, with their normal 6 member lineup, Ricardo Cruz, Aniki, and Sakamoto.

I just don't like their whole medley format and only singing the TV size versions of anime OPs though. It's much more awesome if they actually sang the whole 3-5 minutes of the song.