Rusu Masakage

Rusu Masakage (1549–1607) was a senior retainer of the Date clan and uncle of Date Masamune, a politician and military commander who played an important role in Masamune's domination of Ōshu and the establishment of the Sendai domain. While inheriting the Rusu clan name, he served as a core member of the Date family, leaving particularly notable achievements in developing the Sendai castle town.

Masakage was born as the third son of Date Haruyoshi and grew up as a member of the Date clan. During the Battle of Suriagehara in 1589, when Date Masamune defeated the Ashina clan, Masakage also participated and earned military merit. After Toyotomi Hideyoshi's Ōshu Settlement (1590), as the Date clan's domains were drastically reduced, Masakage supported Masamune as his right-hand man in diplomacy with the Toyotomi government.

After the Battle of Sekigahara (1600) and the establishment of the Sendai domain, Masakage became central to domain administration. He played a leading role in developing the castle town around Sendai Castle (Aoba Castle), greatly contributing to the formation of Sendai's urban foundation. He also assisted Masamune in diplomacy, protecting the Date clan's interests in negotiations with the shogunate.

In his connection to swords, the Rusu house, as a branch of the Date family, benefited from the Date family's sword culture, and Masakage is thought to have possessed fine swords. He is also said to have been involved in managing the collection of famous swords from the Tōhoku region collected by the Date clan, and is evaluated as one of the people who laid the foundation for the Sendai domain's sword culture.