The Kai is one of Japan's native breeds, and originates from the Kai district in Yamanashi. It is the only Japanese breed that may only come in brindle - the colours should be strong and there should be no white markings. It is a bit heavier-set with a more powerful head than most native breeds. The kai was originally used to hunt mainly boar and deer in the mountains. It was proclaimed a national symbol in 1934.

The kai should be pretty powerful with a thick neck, high withers and powerful legs. The head should be wide with a medium stop, the ears larger than in other japanese breeds. The tail is set high, thick and curved or curled over the back. The coat is hard and straight, the colour always brindle.