Google leads me to this site where it shows auction lots? Not sure, but some works described as "print" but some as "acrylic on paper" etc.
http://www.artnet.com/artists/yoshitaka-amano/
Can't find any "official" info from japanese wiki :( He doesnt seem to keep website now? Only blog
Yeah, he sells lithographs through Art Viviant, but most of the originals I've found are in that superflat pop art style. Nothing wrong with that, just out of my price range and not the typical wispy, ethereal look I associate with him.