The Toshogu is the mausoleum of Tokugawa Ieyasu, founder of the Tokugawa shogunate which ruled Japan for over 250 years until 1868. The shrine is dedicated to the spirits of Ieyasu and two other of Japan's most influential historical personalities, Toyotomi Hideyoshi and Minamoto Yoritomo.

(wording from this site: http://www.japan-guide.com/a/html/nikko_e.html)