I've been trying to get another U.S. System 3.0 card for years, because back when I had both, at least one of them would run on either region. Maybe it's just random cards or hardware, but he could be telling the truth. He could also have a U.S. card in a japanese case. The auction does say that the manual is japanese, so the only part he'd be possibly lying about would be if he really tested it on a Turbo-CD.