Sadamitsu was one of the Kōga Clan's ninja dogs, which was at war fighting on Iga's side. He was a Genin (jap.下忍), a low ninja.
Even though, Sadamitsu was a Kōga ninja dog he refused to betray Ōzaru and his clan. When both clans were allies Sadamitsu greatly respected Ōzaru as a teacher refusing to fight against him but warn of his clan's plans.
When the Kōga Clan betray allies Iga teaming with Nobunaga Oda. Sadamitsu runs risking his life to warn the Iga ninjas of the impending attack, because he greatly respects ninja dog Ōzaru, which is his former teacher.
Ryōga, Resshi and Juga went chasing Sadamitsu, but Ōzaru and his comrades came to his aid by accident scene. Sadamitsu revealed to the Iga ninja dogs that Nobunaga would attack their territory in the near future. Other Kōga ninja dogs irritated by the discovery of their plan and threatened to kill Sadamitsu, if he tried to return home. Sadamitsu as well as other dogs were removed quickly when Ryōjun Itō enters the scene, though Ryōjun lived to see the Sadamitsu.
Sadamitsu later meets Kotobuki, when this is going back a message from exporting. He says one of the dog, after which their paths diverge. Later Ōzaru sees Sadamitsu on the roof, with Ryōjun entering the meet Danbo Momochi and other Iga ninjas.
Sadamitsu will be seen later fighting with the Iga dogs against the Koga ninja. He remains outnumbered, losing his right eye and get a sword side. Ōzaru arrives to help Sadamitsu, but Kōga's leading ninja dog Jirōta puts the sword Sadamitsu's throat, preventing Iga ninja dog from attacking. Sadamitsu decides to sacrifice himself so that he could not be held hostage to use against Ōzaru, and strikes against the sword blade. He die quickly from his wound.