At last, there is a free, smartphone-friendly online service in Japan for easily sharing and submitting detailed backcountry plans via the web. MT-Compass is a free, Japan nation-wide service (https://www.mt-compass.com/) that allows backcountry travelers to submit their backcountry skiing, mountaineering, and hiking plans directly to regional police databases via the web. The English version of the MT-Compass site (https://www.mt-compass.com/) is a bit clunky, but using my instructions below, you'll get the gist of it quickly.