A site with Esperanto explanations of Japanese terms is at http://jega.hp.infoseek.co.jp, spread over three pages:
http://jega.hp.infoseek.co.jp/terminaro/esp_tekn_A-H.htm
http://jega.hp.infoseek.co.jp/terminaro/esp_tekn_I-R.htm
http://jega.hp.infoseek.co.jp/terminaro/esp_tekn_S-.htm .
Charles Matthews Some interesting definitions here, as far as I can gather; and at least not copied from existing sources, as so many web sites are.
HolIgor: As far as I can gather this is not the explanation of the Japanese terms to people who speak Esperanto, this is introduction of the Esperanto terms to people who speak Japanese.