The girl Fang Jiang (played by Aya Kiguchi) was originally a low-level maid in a geisha house. She devoted herself to serving her sister Kikuno (played by Hitomi Hasebe), who was the head geisha. However, Kikuno was bossy and unfeeling. By chance, Fang Jiang's extraordinary physical strength was discovered by the young master Yingye Guang (played by Takumi Saito) of Yingye Iron. Yingye Iron is ostensibly a large family-owned steel company, but secretly it is ordered by the state to undertake the manufacture of weapons. At the same time, its founder Yingye Quanshan (played by Taro Shigaki) has an ulterior ambition. He recruits girls who are frustrated in life and trains them into geisha killers with both beauty and lethality, and even strengthens the girls' strength through mechanized transformation of the body. The ignorant Fang Jiang and Kikuno were deceived into Yingye Iron, and the sisters were forced to kill each other. In the process, they continued to strengthen their training and transformation in order to surpass each other, and then became indispensable robot killers for the Yingye family. However, as the mission progresses, Fang Jiang gradually discovers the preciousness of family affection and the ugly intentions of the Yingye family...