Chugoku Nature Trail Resources
Traildino is a trail hiking database that offers some basic information about trail. It has a few of the GPS maps listed but it is very scant in this area. Provides overview of complete trail.
This trail is divided into five prefectures, and each prefecture provides their own maps. Depending on the prefecture they can be downloaded or must be requested by mail. There is no link for Yamaguchi Prefecture. I have been unable to find additional information this prefecture.
All links are in Japanese.
Yamaguchi Prefecture
This a government website that breaks the trail section by section. You can navigate it by clicking the pictures of the section you want to see. It is one of the more comprehensive sites I have found. There are no topographical or GPS maps on this site. This site also has other hiking trails in Japan.
For the Chugoku Trail the Nature Lovers club also provides detailed brochures for this trail.