Many young guys are sent to the so-called "Spy School" at Nakano Institution in order to develop their skills as superb agents of surveillance. In order to submerge themselves in training, they forget their names, their families, and even their lovers. Jiro, one of the cadets, was able to pass the final exam by successfully capturing the secret code used by the English army. However, he finds himself at a crossroads when it is revealed that his fiancée, Yukiko, is working for the adversary.