The School of Spies (1966)

At the Nakano Institution, aspiring spies undergo rigorous training, sacrificing their identities and personal ties to become elite operatives. Among them is Jiro, who triumphs in his final exam by decoding a crucial English army secret. His success, however, is overshadowed when he discovers that his fiancée, Yukiko, is an enemy spy. Faced with a moral dilemma, Jiro must navigate a treacherous path between love and loyalty, ultimately questioning everything he has learned at the institution.