As a FCI-judge for Akita, American Akita and Shiba, I am looking after more information about the other Japanese breeds: Hokaïdo, Kai, Kishu and Shikoku.
Who can help me with this?

Check out some of the places that have breed profiles. Also there is the Tosa Inu and Jindo.

Petpublishing.com has links to descriptions of various breeds. I performed a quick search and found some interesting information on at least one of the breeds you noted.