Sergeant Eiji Honma has been assigned to the Shanghai military police. Not long after assuming his new post, he is summoned by Captain Masayuki Oikawa. Oikawa orders Honma to conduct an internal investigation and uncover an enemy agent who's infiltrated their ranks. As he explains the mission, they hear an explosion...

Former diplomat Kiichiro Shirahata is suspected to have illegally gained knowledge of the Imperial Army's top-secret "Grand Strategy." Investigating in secret, Jirou Gamou makes contact with Shirahata's old friend, the British consul Ernest Graham.

It's spy vs. spy as D-Agency and Wind Agency both race to prevent Japan's "Grand Strategy" from falling into enemy hands.