Lifespan: Unknown to Tenshō 7 (1579) (?)
Other Names: Izumi-no-kami
Father: Tendō Yorimichi
Siblings: Yorinaga, Yorisada
Wife: [Formal] Daughter of Shirotori Yoshihiro, [Second] Daughter of Kokubun Moriuji
Children: Daughter (consort of Mogami Yoshiaki), Yorizumi, Higashine Yorikage
Tendō Yorisada served as a bushō during the Sengoku period. Yorisada serve as the head of the alliance of powerful kokujin, or provincial landowners, known as the Eight Shields of the Mogami (or, the Eight Shields of the Tendō). He was the sixteenth head of the Tendō clan (a branch of the Satomi clan) and the lord of Tendō Castle, built on Mount Maizuru in Dewa Province.
Yorisada was the second son of Tendō Yorimichi. After the death of his older brother, Tendō Yorinaga, Yorisada inherited the headship of the clan. He wed a daughter of Kokubun Moriuji and maintained an alliance with the Date clan. In terms of lineage, the Tendō clan were an illegitimate branch of the Satomi clan descended from the Seiwa-Genji. In the mid-fourteenth century, during the Nanboku period, Shiba Kaneyori moved from Mutsu Province to the Mogami District of Dewa. Thereafter, for two successive generations, the family adopted their heirs, becoming part of the bloodline of the Mogami clan and under their command. Owing, however, to a weakening of the branch of the Mogami in charge of regional landholding families based on divided inheritance under the leadership of a main heir, Yorisada expanded his power and, in the early Sengoku period, rose to a level of stature whereby he was treated by the Kamakura kubō on the same level as the Mogami.
After the death of a family member named Higashine Yoritaka without an heir, Yorisada sent his second son, Tendō Yorikage, to become the successor to the Higashine clan. In 1574, upon the outbreak of the Tenshō Mogami Conflict among opposing members of the Mogami clan, Yorisada sided with Mogami Yoshimori and Date Terumune, attacking the Sagae clan. After Yoshimori and Terumune reached a settlement with Yoshiaki, Yorisada also reconciled with Yoshiaki. In 1577, Yoshiaki mounted an assault against Tendō Castle, but Yorisada successfully defended the stronghold with support from members of the Eight Shields of the Mogami. As a condition for settlement, Yorisada permitted his daughter to be sent as a consort to Yoshiaki.
There is a theory that Yorisada died in 1579. He was succeeded by his son, Tendō Yorizumi.