Answer:
The vast majority of people who lived in medieval Japan were Native Japanese because there were pratically no foreigners.
Most medieval Japanese were farmers who lived in a feudal society much like that of medieval Europe. They were subjected to the power of a few feudal lords, who in Japanese are called damyos.
These lords had samurais (the Japanse equivalent to the European Knight), fighting for their protection. Finally, they swore loyalty to the Emperor, but they wielded most of the real power.