Tōyama Masakage served as a bushō during the Sengoku and Azuchi-Momoyama periods.  He was a retainer of the Gohōjō clan.

Masakage was born as the third son of Tōyama Tsunakage.  Owing to his position as the third son, he was not in the line of succession and entered the priesthood.  In 1564, at the Second Battle of Kōnodai, his father and older brother, Tōyama Hayato-no-suke were killed in action so he returned to secular life and inherited the headship of the clan as well as his father’s role as the chamberlain of Edo Castle.  Similar to his deceased father, he received one of the characters from the name of his lord, Hōjō Ujimasa and adopted the name of Masakage.

Masakage also inherited from his father responsibility for managing negotiations with Ashikaga Yoshiuji, the koga kubō.  In a letter that Yoshiuji sent to Masakage in 1567, Yoshiuji requested 300 to 500 reinforcements from Edo Castle to respond to Sōma Harutane.  It is therefore surmised that Masakage was in a position to individually mobilize a force of that size.

Later, pressure increased from elements opposed to the Hōjō as well as from the Echigo-Uesugi clan.  As a result, Edo Castle was regarded as one of the vital strategic locations whereupon a family member named Hōjō Ujihide was of higher rank than Masakage appointed to replace Masakage at Edo Castle.  As a result, Masakage transferred his role as chamberlain of Edo Castle and moved his base in the direction of Shimōsa Province to contain the Satomi clan and those forces opposed to the Hōjō.

Masakage died in 1580.  He was succeeded by his eldest son, Tōyama Naokage (Saemon-no-taifu).  His grandfather bore the same name of Tōyama Naokage. Saruwatari Morimichi is considered to be Masakage’s second son.