they probably dont know systema. as far as i know japanese thinks their martial arts is the best and they rarely interested in foreigner arts because they hate foreigners. and why would they need russian systema they have their own ju-jitsu and judo goshin jutsu no kata these two is basicaly same stuff for self defence against knives and other weapons and actually if you talking about Ryabko systema then i have bad opinion about that one because mr. Ryabko is fat ass and all his art (?) based on one persons experience (that is bad) and that person dont even have proper experience to teach peoples self defence. russian martial arts is prety much full of bull... because they allways mixing street fighting with their "legendary" specnaz and these two is not really good for each other because street fighting is for streets and for civilians and it should not be mixed with millitary system and specnaz is not even millitary system anymore nowdays it only serves for show. yes for show. all specnaz systema is for show nowdays it have nothing to do with real millitary trainings which is not about fists and knives anymore.