Boris the Manskinner is a former Russian military officer who orders a Mongolian soldier to skin Yamamoto alive. Later, Mamiya encounters Boris in a Russian prison camp. While in the camp, Mamiya allies himself with Boris to stay alive. Before getting sent back to Tokyo, Mamiya tries and fails to kill Boris. In response, Boris can only laugh at Mamiya. He is a callous and cruel man with no value for human life.