Lifespan: Meiō 4 (1495) to Kōji 2 (1556)
Title: Keeper of Imperial Archives, Governor of Suruga
Clan: Daidōji (descended from the Taira clan)
Lord: Hōjō Sōun → Hōjō Ujitsuna → Hōjō Ujiyasu
Father: Daidōji Shigetoki
Daidōji Morimasa served as a bushō during the Sengoku period. He was a retainer of the Gohōjō clan.
Morimasa was born as the son of Daidōji Shigetoki. Shigetoki accompanied Hōjō Sōun (Ise Moritoki) to Suruga Province. Among the retainers of the Gohōjō, the Daidōji became one of six families of elevated status. There are various theories as to whether Morimasa was the father, grandfather, or great-grandfather of Daidōji Masashige, and the facts remain uncertain. There is another theory that Morimasa (rather than Shigetoki) accompanied Sōun to Suruga.
Morimasa was a nephew of Sōun (first known as Moritoki; strictly speaking, the son of a cousin) and was heavily relied upon for his administrative acumen. He received one of the characters in his name from Moritoki. After the death of Sōun, he continued to serve Hōjō Ujitsuna.
During this period of service, Morimasa joined Kasahara Nobutame serving as magistrates for the reconstruction of the Tsurugaoka-Hachiman Shrine that was burned down in the Battle of Tsurugaoka-Hachiman against Satomi Yoshitoyo. He also served in the honorary role to place the black-lacquered head gear known as an eboshi on Hōjō Tamemasa (the second son of Hōjō Ujitsuna) at his coming-of-age ceremony and conferred upon him a character from his name. After Tamemasa became the lord of Tamanawa Castle at a young age, Morimasa served as his guardian. Morimasa was originally an official for the eastern portion of Sagami including the Kamakura District and, owing to his role as a guardian for Tamemasa, is surmised to have become the official for Kamakura.
After his lord changed from Ujitsuna to Ujiyasu, he served valorously, fighting against Ōgigayatsu-Uesugi Tomosada at the Siege of Kawagoe Castle in 1546. After the battle, he served as the chamberlain of Kawagoe Castle. His contribution of land to the Jōchi Temple in Kamakura in the fifth month of 1550 is the last reference to him in historical records. On 7/12 of an unknown year, he died at the age of sixty-two.
Morimasa was succeeded by his eldest son and designated heir, Daidōji Kanekatsu (Shigeoki).