藩主 (hanshu) refers to the lord or ruler of a feudal domain in Japan during the Edo period (1603-1868). Each藩 (han) was a semi-autonomous region governed by a藩主, who was responsible for the administration, military, and economic affairs of their territory. The藩主 was typically a member of the samurai class and held significant power within their domain. The藩主 was subordinate to the shogun, the military leader of Japan, and had to pay taxes and provide military support when required. The藩主's authority was often hereditary, passed down through generations within a family. This system played a crucial role in maintaining local governance and stability in Japan's feudal society.