Second son of Toyama Tomotada, head of the Naegi Toyama clan. In 1574, when Kiso Yoshimasa, a vassal of Takeda Katsuyori, invaded eastern Mino, his father Tomotada, lord of Adera Castle, and his three sons put up fierce resistance, wounding senior Kiso retainers, but Tomoshige was killed in the fighting. Adera Castle fell in this battle and was never rebuilt.

A young warrior of the Naegi Toyama clan remembered for his bravery in standing against a much larger force alongside his father Tomotada and brothers.

Tomoshige's death and the fall of Adera Castle are remembered in the history of the Naegi Toyama clan as an episode illustrating the intensity of the Takeda invasion of eastern Mino in 1574. The ruins of Adera Castle in Ena City, Gifu Prefecture, still preserve stone walls and terraced enclosures in the mountains today.