Unnamed, only known in guides as "One-Armed Man"
He was an elderly man who wore a fedora and a heavy trenchcoat, hiding most of his body. He had a large hooked nose and visible wrinkles in the shape of electric currents, and covered his eyes with a pair of small sunglasses.
His initial design had him with two arms and a hook on his right hand, this was later changed to have him missing his left arm and having a machine gun in place of his hand.
He also initially only had one lens blacked out in his glasses, implying he may have been blind in his left eye before Ishinomori altered the design to have him wear the sunglasses.
His left arm hid a high powered machine gun, which he could whip out at any time.