Minamoto no Mitsunaka (源 満仲, April 29, 912 October 6, 997), son of Minamoto no Tsunemoto, was a samurai and court official of the Heian period of Japanese history. Mitsunaka belongs to the Seiwa-Genji branch of the Minamoto clan which traces its origin back to the emperor Seiwa.
He loyally (if not selflessly) serves several successive Fujiwara regents (sesshō and kanpaku) beginning with Fujiwara no Morotada.
Mitsunaka allied himself with the latter in 969, implicating Minamoto no of Takaakira - Morotada's main political rival - in a plot against the throne.
It is not clear whether these accusations are true, but Takaakira is sent into exile, putting Mitsunaka firmly in Morotada's good graces. Later, Mitsunaka aids Fujiwara no Kaneie in his plot to force Emperor Kazan to take his Buddhist vows and abdicate in favor of Fujiwara's seven year old grandson.
Mitsunaka's association with the Fujiwara clan made him one of the richest and most powerful courtiers of his time. He was the acting governor (kokushi) of ten provinces in Japan, including Settsu, which became the pillar of his military and economic power.
In addition, Mitsunaka inherited his father's title chinjufu-shōgun, commander-in-chief of the northern defense. The protective/client relationship between the Fujiwara and the Seiwa-Genji continued for nearly two hundred years after Mitsunaka's death. In fact, the Seiwa-Genji came to be known as the "teeth and claws" of the Fujiwara.
Mitsunaka married the daughter of Minamoto no Suguru, of the Saga-Genji branch of Minamoto. He had three sons: Minamoto no Yorimitsu (who became the hero of a large set of folklore pieces), Minamoto no Yorinobu and Minamoto no Yorichika.
In his last years, Mitsunaka retired to his mansion in Tada, a town located in the province of Settsu. For this reason, he is also known as "Tada Manjū" ("Manjū" is the Sino-Japanese reading of the characters for "Mitsunaka"). His descendants are sometimes called the Settsu-Genji or the Tada-Genji6.
Mitsunaka appears in the anime Otogi-zōshi, as well as fictionalized versions of a number of other historical figures.