During the reign of Tokugawa Iemitsu, the third shogun of the Edo shogunate, a strange disease called "akasura pox" spread throughout Japan. The disease was a dreadful illness that "infected only young boys" and, if contracted, could lead to death "in a few days. No cure or treatment was ever discovered, and as a result, the male population plummeted to one-fourth that of the female population, drastically changing the social structure of Japan. Boys were bred to be scarce stallions, girls replaced boys as the workforce, and all family businesses were passed down from woman to woman. In Edo Castle, too, the shogun's position was handed over to a woman after the third shogun, Iemitsu, and the inner chambers of the shogun's palace surrounded rare boys as if they were proof of the shogun's prestige, creating a world of men commonly referred to as the "three thousand beautiful men.