Kaku[12] is a masked agent of CP0.[2] He was previously an assassin of CP9, operating undercover in order to obtain the Pluton blueprints from Iceburg.[5] While undercover, he acted as one of the five foremen of Galley-La Company's Dock One, specializing in mechanics, diagnostics, and housecalls.[6] He is a major antagonist in the Water 7 and Enies Lobby Arcs, and a supporting antagonist in the Egghead Arc, later turned reluctant temporary ally of the Straw Hat Pirates during the latter Arc.