Masao is a member of Kyōshirō's pack and one of the youngest.
He was left with the Kōga Elder along with the other puppies from his pack.
Later he and the others joined the fight against Victor and the other Russian Army.
He participated in the battle against the hybrid bears.
Masao and Ou army have caught in the volcanic eruption. He survives and is one of the Ōu army Jinemon Kurohabaki locks the mine. Later, the dogs are released and they participate in the final battle Kurohabaki Masamune against the troops.