Lifespan: Eiroku 11 (1568) to Unknown
Other Names: Yorihisa, Saburō (common), Kai
Lord: Date Masamune
Father: Tendō Yorisada
Mother: Daughter of the Kokubun clan
Siblings: Sister (consort of Mogami Yoshiaki), Yorizumi, Higashine Yorikage, sister (wife of Akiu Naomori)
Wife: [Formal] Daughter of Hosokawa Naomoto
Children: Daughter (wife of Yoshikawa Takahiro)
Adopted Children: Tendō Shigeyori (second son of Rusu Masakage)
Tendō Yorizumi served as a bushō during the Sengoku and Azuchi-Momoyama periods. Yorizumi served as the seventeenth head of the Tendō clan, an illegitimate branch of the Satomi clan. He was the lord of Tendō Castle built on Mount Maizuru in Tendō in the Murayama District of Dewa Province. Yorizumi was originally known as Yorihisa.
Yorihisa was born as the son of Tendō Yorisada, the lord of Tendō Castle. In 1579, following the demise of his father, Yorihisa, at the age of twelve, inherited the headship of the clan.
His sister, Tendō Gozen, was married to Mogami Yoshiaki, yielding a familial relationship between the Tendō and the Mogami. Nevertheless, Yorihisa was an independent landowner serving as the nucleus of an alliance of powerful kokujin, or provincial landowners, known as the Eight Shields of the Mogami (or, the Eight Shields of the Tendō). Moreover, his mother was the daughter of Kokubun Moriuji, a senior retainer of Date Masamune so he also had ties with them. Despite Yoshihisa’s alliance with the Mogami clan who led an organization of regional landholding families based on divided inheritance under the leadership of a main heir, Mogami Yoshiaki took in the Kurazō clan and others who were under the command of the Tendō so that members of the Tendō clan such as the Kaminoyama and Hosokawa Naomoto (Yorihisa’s father-in-law) capitulated one after another to the Mogami. Finally, in 1582, soon after the death of Tendō Gozen, Yorihisa incurred an attack by Yoshiaki at Tendō Castle. Owing to the support of members of the Eight Shields of the Mogami, he was able to defend the stronghold, resulting in a stalemate.
In the sixth month of 1584, the Shiratori and Sagae clans were destroyed in succession, while Nobesawa Mitsunobu, the most potent member of the Eight Shields of the Mogami, was lured away by a retainer of the Mogami named Ujiie Morimune and betrayed his former allies in favor of the Mogami. These events suddenly turned the tide toward the Mogami, leading to acts of collusion by the remaining defenders. In the tenth month, Tendō Castle fell.
Yorihisa turned to the original family of his mother, the Kokubun, to escape to safety. Thereafter, through the assistance of Akiu Naomori, he stayed in Akiu. On 1/13 of Tenshō 18 (1590), Yorihisa ascended Kurokawa Castle to give thanks to Masamune. During the Bunroku era (1593 to 1596), Masamune appointed his family as a ranking member of the Sendai domain and he was awarded a fief of 1,000 koku in Rifu in the Miyagi District of Mutsu Province.
Later, he changed his name to Yorizumi and called oneself Kai.
Yorizumi did not have children so the second son of Rusu Masakage became his adopted heir and took the name of Tendō Shigeyori.