Not an expert but I'll give my two cents. Oda and Tokugawa would probably be...spirited away so to speak. Gunpowder weaponry would be introduced earlier as a result of the invasion, and I'm guessing that the position of Emperor/Empress would become puppet to the Mongols as it was so central to the Japanese social order, by which I mean they would be forced to marry a Borjigin princess,and give Japanese Princesses as concubines. Pro Mongol clans would be given greater benefits etc. Kublai wanted Japan to be tributaries which means that for a time they would be, and probobly be involved in greater trade, and less piracy. I don't believe the Mongols have the forces to garrison Japan, just force, and instill vassalage/tributary status on the Chrysanthemum throne. Japan in my opinion would thus go the way of Vietnam whom after bloodying the Mongols ultimately opted to pay tribute rather then ferment endless war. When the Ming rise or a weak Emperor takes the reigns of the Mongols then the Japanese may take the chance to shake their vassalage off. Just my thoughts.