Probably the original, but I'm not certain since I stopped supporting Koei after DW5. All they do is re-skin the game, alter the maps a bit, add one or two movesets and that's it. Then they release expansion 'games' that only have a few new modes and *gasp* weapons. They're just milking a dying franchise. If you want an absolute answer then go ask on their forums, but their forums have dying lately ever since they enforced new rules.