Nagato Sakurai is a captain in the Japan Self-Defense Force serving within its secret service branch. He is initially tasked with monitoring Tony Stark from a distance when Stark arrives in Japan to build a new arc reactor and unveil the Iron Man Dio armor. During one of Stark's pursuits of Zodiac agents, Sakurai becomes caught in a traffic jam Stark orchestrated, bringing him into direct contact with the hero. After the Iron Man Dio armor goes rogue and targets Japan, Sakurai becomes one of Stark's key allies. He pilots the Ramon Zero armor, a powered suit developed by the JSDF for him, which allows him to fight alongside Iron Man against the Zodiac organization and their advanced mecha. Sakurai is a dutiful and capable soldier who prioritizes the safety of his country. He assists Stark multiple times, notably helping the seriously wounded Stark survive and recover, and later conferring with him on a plan to launch Tony into high altitude using a jet as part of a multi‑stage rocket to combat the Zodiac agent Aquarius. Through his cooperation with Stark, Sakurai evolves from a distant observer to a trusted comrade, demonstrating resourcefulness, loyalty, and a willingness to go beyond standard military protocols when the situation demands it. His notable ability lies in his piloting skill with the Ramon Zero armor, which enhances his combat effectiveness and durability, making him a practical ground‑based support for Iron Man’s aerial operations.