The agent snickered. “You burned Aka-hebi alive, so don’t fear the merciful bullet, Tadashi.” Tadashi had burned Russian prisoners alive and performed many horrific acts under the Unit 731 banner for his Emperor. He was following orders—doing as he was told—for medical science.

In my humble opinion, after the agent's line, it is unnecessary to provide such a thorough explanation to readers—particularly in the middle of such intense scene.

On another note, I just found out Tadashi was still alive this whole time! 😮