There are some free digital maps compatible with the digital maps of the Geographic Survey Institute Japan.
(a) "Free Digital Map"
These maps were created by DAN Sugimoto using conical approximation according to the "Yamaotaku" data. it covers whole Japan with 250m grid and 1 km grid resolution. It lacks reality because ot its conical approximation.(b)Other free digital maps"How to get them "3D Landscape CG, @nifty FYAMAP LIB-3, "Enjoy Mountain and Map with PC (Japanese) Vol.2 "CD-ROM
There are also other free digital maps created by the members of the @nifty FYAMAP. They digitized their favorite areas from the maps and uploaded to the library. Many famous mountain areas are going to be available. These data have 50m grid resolution and have almost comparable quality with the digital maps from the Geographic Survey Institute. Mr. Kisaku is trying to cover whole area of the north Alps in Japan.(How to use them)"How to get them" @nifty FYAMAP LIB-3
They can be used just as the same way for the digital maps from the Geographic Survey Institute. In same cases except for the "Free Digital Map" there might be a format conversion necessary. Please refer to each document for the data.