Tōyama Yasuhide served as a bushō during the Sengoku period. He was a retainer of the Hōjō clan of Sagami Province.
Yasuhide was born as the lineal heir of Tōyama Yasumitsu, a retainer of the Hōjō.
Yasuhide served as sōja, or intermediary for communications with the central authorities, on behalf of Hōjō Ujiyasu. From around 1560, he served as a representative of the Hōjō in the Miura District of Sagami. Together with his uncle, Tōyama Tsunakage, he defended the front lines against the Satomi clan. After the death of Ōta Ujisuke, Yasuhide entered Iwatsuki Castle and served as its chamberlain. Later, after Takeda Shingen invaded Suruga Province, Yasuhide deployed as a member of the Hōjō army to Suruga. During the formation of an alliance between the Hōjō and Uesugi Kenshin, Yasuhide accompanied his father, Yasumitsu, as representatives of the Hōjō clan. In 1570, Yasuhide and Yasumitsu holed-up in Nirayama Castle in Izu Province during an assault by the Takeda army. Thereafter, Yasumitsu went to serve Uesugi Kagetora in Echigo Province, but, as a close associate of Hōjō Ujimasa, Yasuhide remained in the Kantō and managed communications with the Uesugi clan.
There are various theories regarding his demise. According to one theory, during the succession struggle known as the Otate Conflict, Yasuhide joined his father on the side of Kagetora and, after getting involved in the discord, took his own life. Alternatively, he continued to serve the Hōjō until the Conquest of Odawara and, after the fall of Odawara Castle, was engaged in service by Nakamura Kazuuji, a daimyō, under the name of Tōyama Saemon.