The Kai Ken is a medium-sized dog and is one of the six native Japanese breeds or Nihon Ken. Traditionally used to hunt a wide range of game in the mountains of Japan, the Kai Ken is considered a rare breed even in Japan. The Kai is highly intelligent and learns quickly. They seem to learn as fast as the other Japanese breeds if not faster. They are not as independent and are more willing to please their companions. The Japanese describe the Kai Ken as a trustworthy guardian and extremely devoted to his master.