Born in 1544 as the eldest son of Date Harutane, 15th head of the Date clan. He succeeded as 16th head at age 21 in 1565. Known to history as Masamune's father, he was himself an accomplished ruler who expanded the Date domain considerably through both diplomacy and military power. So beloved by his people that he was called "My good lord." In 1584 he handed the headship to his son Masamune at age 18, clearing the way for the younger man's ambitions. In the tenth month of 1585, an unprecedented incident occurred: Hatakeyama Yoshitsugu of Nihonmatsu, nursing grievances over territory disputes, seized Terumune in a sudden abduction during what appeared to be a routine meeting—the "Awanokasu Incident." Yoshitsugu fled toward the Abukuma River using Terumune as a shield; when Masamune's pursuers cornered them, Terumune reportedly ordered his son to "shoot through me." On Masamune's command, retainers fired, and both Terumune and Yoshitsugu were killed at the river's edge. He was 42. The shock of his father's death gave Masamune a ferocious drive to dominate Tohoku.

Gentle and sincere, with deep trust from his retainers. Accomplished in both civil and martial arts. He recognized Masamune's genius and stepped down early to allow the Date clan to flourish.

A wise lord who laid the groundwork for Masamune's rise. His dramatic death is etched deeply in Date history, and the Awanokasu Incident is remembered as emblematic of Masamune's ruthless resolve. Terumune's reign formed the foundation of the Date clan's growth.