Lee Lan, a member of the PetroChina Oil Project, was killed in Shanghai. In the shadow is a dark triangle of House of Representatives member Yamada and his secretary, Nojima, and Vice President of Japan-China Oil Company, Miki Lee Ran was raped and killed by a paraphilia Yamada, and the incident was buried in the darkness. In order to "clean up" this incident, Anna, a member of the "Dark Angel", is ordered, but an unexpected new target appears while performing the mission.