Historically, after much struggle, Tokugawa Ieyasu didbecome the seii taishogun, the "great general who subdues the barbarians" and the ruler of Japanwith the emperoras afigurehead.
The role wasn't a complete sinecure: the ruling warlord, Tokugawa Ieyasu, ordered the seppuku, or ritual suicide, of one of Koetsu's circle, the tea master Furuta Oribe, for some real or imagined disloyalty.