was a Japanese samurai of the late Sengoku era through early Edo era. The son of Oniniwa Yoshinao, Tsunamoto served the Date clan, and by the end of his life was the only Date retainer who was both older than and outlived Date Masamune

Date Masamune

was a regional strongman of Japan's Azuchi-Momoyama period through early Edo period. Heir to a long line of powerful daimyo in the Tōhoku region, he went on to found the modern-day city of Sendai...

. Tsunamoto succeeded to the family headship following the death of his father at the Battle of Hitodoribashi in 1585. Deeply trusted by Masamune, he was made a senior retainer at the young age of 35. Together with Katakura Kagetsuna

Katakura Kagetsuna

was a Japanese samurai of the Katakura clan during the late Sengoku period. Also known by his court title, Bichū no Kami , or more commonly, as Katakura Kojūrō. Together with Oniniwa Tsunamoto and Date Shigezane, Kagetsuna was known as one of the "Three Great Men of the Date Clan"...

 and Date Shigezane

Date Shigezane

was a Japanese samurai of the late Sengoku through early Edo eras. Founder of the Watari-Date clan. A senior retainer of the Date clan of Sendai, he was a cousin of Date Masamune on his mother's side, and a cousin of Masamune's father Date Terumune on his father's side. Together with Oniniwa...

, Tsunamoto was known as one of the "Three Great Men of the Date Clan". After the Bunroku Campaign, he assumed the name of Moniwa on Toyotomi Hideyoshi's orders, making his full name Moniwa Nobumoto (茂庭延元).