May 1947 . Two years have passed since Japan was defeated in the Pacific War , and it was placed under occupation rule by GHQ . Sango Kiri, a former spy who came back to Japan from the continent , was unable to find his whereabouts, and spent days in a daze.

One day, Kiri happens to meet Seishiro Saruta , who was his senior in the army, and ends up staying at Saruta's house. Saruta lived as a manager of Kastori magazine publisher, but Saruta had another "back face". It was the face of a spy hired by the mysterious Johansen .

Asked for help from Saruta, Kiri decides to live as a spy again, working behind the scenes as the "National Dog" .