Final answer:
The shogun was the powerful military leader who ruled Japan.
Step-by-step explanation:
The powerful military leader who was the true ruler of Japan was the shogun. Although the emperor held the ceremonial title, the shogun had the actual authority and governed Japan from 1185 until 1868. The shogun commanded the daimyo, who were local samurai warlords, and their samurai warriors. The shogun's power was solidified during the Edo period when the Tokugawa Shogunate unified the country.