Also known as: Oniniwa Tsunamoto, Moniwa Nobumoto

A vassal of the Date Clan under Date Masamune whose father, Oniwa Yoshinao, died at the Battle of Hitotoribashi. Masamune's trust in him and his admininstrative skills were such that he was given important administrative duties over other key retainers at the age of 38.

In 1590, when Toyotomi Hideyoshi suspected Masamune of treason, Tsunamoto went to the capital in his lord's defense. Hideyoshi was so impressed by his ability that it was said that he gave one of his concubines to Tsunamoto.

Tsunamoto would later serve Masamune's son, Date Hidemune, with the same faithfulness.