Y, both of those reasons are related with poor army/staff tradition. EU is no match for the Mongol generals.
Jap's were always trained well and very disciplined but not that great when it comes to generals/army tradition and equipment. They were inexperienced in managing such a large force, side effect of being an island nation. Just clan wars between each other. Also the style of warfare that was customary within feudal Japan involved single combat, even on large battlefields. Plus, Jap's were poorly equipped since the Mongol invasion, which led to the invention of the Katana. Cuz their toy swords couldn't even cut the mongol leather.
Anyway, everything was changed after 14th century. Blacksmiths reevaluate their swords, Generals got experienced and learned their lessons from Mongols. Jap's also adapted the superior foreign weapons which the Mongols possessed(Chinese stuff n gunpowder).
I think we need to specify a time period for this comparison cuz even Krems can rekt Jap's in the 12th century.