Saitou operates as a high-ranking agent within Daiwa Heavy Industries, a pivotal force behind Japan’s isolation and clandestine technological dominance. Portrayed initially as a staunch enforcer of corporate loyalty, he orchestrates a staged viral outbreak to legitimize mass robotic conversion, despite knowing the pandemic’s falsified origins. Embracing the experimental transformation into a synthetic being, he champions the evolutionary superiority propagated by Daiwa’s leadership.

During a covert meeting with foreign delegates, Saitou evades a SWORD assassination by severing his bio-metal limb—a brutal escape that unveils Japan’s illegal biotech endeavors to global observers. His ruthless hunt for SWORD infiltrators in Tokyo fractures when he uncovers his superior, Kisaragi, exempted himself from the robotic metamorphosis. Consumed by betrayal, Saitou confronts Kisaragi, strangling him while decrying the hypocrisy that corrupted their shared vision.

Mortally wounded in the struggle, Saitou expends his final strength freeing imprisoned resistance fighters, ensuring their flight as Daiwa’s headquarters crumbles. This last act of rebellion marks his transformation from corporate zealot to a figure of fractured allegiance, rejecting the ethical decay he once enforced.