The Tosa varies considerably in size, with the Japanese-bred dogs tending to be about half the size of those bred outside the country. The Japanese breed generally weighs between 80 and 120 lb (36,3 - 54,4 kg), while the non-Japanese breeders have focused on dogs that weigh from 130 to 200 lb
Japanese bred or not that's one big bow-wow. The Samurai must have road them in battle.