Lieutenant Sakuma is a first lieutenant in the Imperial Japanese Army who is assigned to the secret D-Agency on the orders of his superior, Colonel Mutou. His official role is to serve as a liaison between the agency and the general staff, inspecting the unit’s operations and reporting back. Sakuma comes from a traditional military background and initially holds a strong disdain for espionage, viewing spycraft as dishonorable and cowardly compared to the straightforward values of a soldier. He is a diligent, honest, and cautious man, dedicated to his duties and loyal to his chain of command. However, his practical, by-the-book mindset often clashes with the unconventional methods and blunt remarks of the D-Agency operatives, particularly those of Miyoshi, who frequently mocks his rigid demeanor. Despite his initial irritation, Sakuma gradually undergoes a significant shift in perspective as he works alongside the spies. He is present during critical operations, such as the tense search of John Gordon’s residence, which forces him to confront the effectiveness of espionage. His relationship with Lieutenant Colonel Yuuki, the head of D-Agency, evolves from suspicion to a grudging respect, and Sakuma begins to appreciate the value of pragmatic intelligence over wasteful displays of honor. By the end of his arc, Sakuma serves as the audience’s moral anchor and entry point into the shadowy world of spies, questioning the ethics of deception while ultimately acknowledging its necessity. His notable abilities lie not in spy tradecraft but in his steadfast integrity, observational caution, and willingness to adapt his beliefs when faced with evidence of the agency’s extraordinary competence.