The predecessor assassin named BAKURYU who cooperated Tylon; his real name is Kato RYUZO All he wanted to have was the mighty power as Zoanthrope. Repeated operations for body reinforcement decomposed RYUZO's body, but there is an organization which saves the liquefied tissues of RYUZO, which were left behind after his death. The organization's name is "YUN CHI Manufacturing, INC." which once was a department of Tylon, and still is in business activities even after the collapse of their main office. YUN CHI Manufacturing, Inc. succeeds in composing a battle robot named "Iron Mall" which is produced on the trial base with the BAKURYU's battle data and the liquefied tissues which conceives physical strength of BAKURYU. But the trial product starts to move recklessly during the test run. And the robot begins to attack Zoanthropes as if it has an intention.
