Set against the backdrop of a fictional World War II in an international Asian city, the story unfolds in Japan where Lieutenant Colonel Yuki, portrayed by Yusuke Iseya, proposes the establishment of a spy training school called “D Kikan.” Concurrently, Kazuya Kamenashi’s character, Kato, is on the brink of execution for defying a superior’s command. However, Kato is recruited by “D Kikan” and undergoes rigorous training before embarking on his inaugural mission as a spy. His task is to acquire the secretive “Black Note” documents from American ambassador Graham. To achieve this, Kato infiltrates the international city, sparking a fierce struggle for the “Black Note” involving Kato, a mysterious woman named Rin (played by Kyoko Fukada), the British and Soviet spy agencies, and a radical faction within the Japanese army.