Cyborg 009: The Cyborg Soldier

Monster Island (1x31)

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Dr. Gilmore calls 004 and tells him to go somewhere. When he gets there, he finds a robot replication of him self that knows his every move. They fight, but the robot wins. Dr. Gilmore tells 004 that this was an experiment to test his ability. He says he should admit that he is nothing more than a powerful weapon, but 004 won't do so. He battles the robot once more, and they fight so intensely that the difference can't be seen between the two. But when the robot prepares to destroy an innocent bird's nest, 004 saves it, proving that he is a human, not a machine. He destroys the robot, then the Dr. Gilmore which also turns out to be a robot. 004 knew the real Dr. Gilmore would never put his life at risk for an experiment.