The Kai Ken is a sturdily built spitz-type dog that is very primitive. Smaller than pictures suggest. They have been designated as a Natural Monument of Japan, and have been preserved under that designation. The Kai is small to medium sized and should fit comfortably at knee height.
They are wily, cunning, and dare I say, goofy. They choose whom they give affection to, and trust me, are not subtle about it. They are also escape artists, which is why I take great care in screening homes. Due to their primitive nature if they are not found they can easily revert back to instincts and become nearly impossible to catch.
The Kai standard calls for only brindle coloration. This comes in different shades, Akatora, Kurotora, and Chutora. There is a recessive gene that expresses cream/white coloration. A Kai that expresses it, should not be bred, and careful consideration when breeding the parents should be taken. Their brindle is also very unique, each dog with differing patterns. A Kai is generally born a solid color (mostly black) and they brindle with age.
The Kai needs a gentle, but firm hand. They are sensitive and respond best to positive reinforcement. The key to this breed is patience. As with most Japanese breeds, they can be stubborn. I find me and my Kai often playing the "I'll wait," game. If they are asked something they either do it, or stare at me and waiting to see if I stagger. Eventually they realize I'm not kidding and they, for example may sit, lay down, or go to their kennel. The best thing about Kai is that you can watch them think, their minds running. It's truly enjoyable to see such a contemplative dog.
Most Kai need very high rewards for training and they are not for beginners unless you can put the time in. They need moderate exercise. Mine are a whole level down than our American Eskimo, and seem to tire much more quick. Once again, they need training. They need that mental stimulation before they become destructive. The Kai also has a teething stage, and it's in that moment you'll realize you have made a grave error not giving them attention.
The Kai is aloof and shy with strangers. You should not force anything, but let them come out of their shell.
IF this has not deterred you in anyway. MAYBE the Kai is for you. A successful pairing is evident and soon you'll realise you can't have just one Kai.
I highly recommend meeting the breed and joining the Nihon Ken forum for more information. You may find another breed there that you see best suits you.