Kohei Oguri is a Lieutenant Commander in the Japan Maritime Self-Defense Force who serves as the Navigation Officer of the Aegis destroyer Mirai. He is a graduate of the National Defense Academy and a former classmate of both the ship's executive officer Kadomatsu and weapons officer Kikuchi. In stark contrast to his fellow officers, Oguri is not consumed by the ethical dilemma of altering history after the Mirai is transported to 1942. Instead, he is a cheerful and open character who believes the crew was sent back in time for a meaningful purpose. This unwavering conviction gives him a distinct role on the ship; he acts as a mood maker, providing emotional support and a sense of normalcy in an extraordinary situation. He is quick to form bonds and genuinely cares for those around him. Oguri's motivations are driven by his heart and his profound sense of duty to his crew and country. He is often the first to advocate for direct action, believing that the Mirai has a responsibility to intervene in the war to save lives. His decisiveness and optimism serve as a vital counterbalance to the caution and strategic analysis favored by Kadomatsu and Kikuchi. Throughout the series, Oguri proves himself to be a highly capable navigator whose skills are essential to the Mirai's survival. His most notable abilities include his strong personal morale, his gift for communication and building trust, and his willingness to take risks to protect his friends. His loyalty to Kadomatsu and Kikuchi is absolute, and he acts as a stabilizing anchor for them. As the story progresses, his initial enthusiasm is tempered by tragedy and hardship, but his fundamental sense of purpose remains a defining characteristic, solidifying his role as the heart of the crew.