John already answered your question, but I'd like to shed some insight on it too. As John said, JGTC (Japanese Gran Touring Championship) althought it is now referred to as Super GT because they have come stateside once in the past, and it is becoming a more international race. (Porsches, C6R's, Ford GT's, and the rest of the J-Spec cars). There are two classes, GT300 and GT500 (similar to ALMS GT1 and GT2). The car bodies are usually completely carbon fiber with widened fenders and bigger wheel arches.
I love the series. I wish it would come stateside more often. The cars are amazing. Its like Japanese Le Mans almost.