Nagase is the dedicated bodyguard and secretary of Kirika Kokuryu, the heiress of the Dragon Bank conglomerate. He is a male adult with black hair that reaches chest length and black eyes. His primary role in the story is to remain constantly at Kirika's side, attending to her security and administrative needs. Because of his perpetual proximity to her, Nagase frequently interprets and explains Kirika's feelings and thoughts to others, acting as a bridge between her and the people she interacts with. His most defining trait is an extremely strong sense of loyalty toward Kirika. This loyalty borders on possessiveness, causing him to view the series' protagonists, Haru Tennouji and Manabu Taira, as direct threats. He dislikes their influence over Kirika and openly regards them as enemies. Nagase's motivations are driven entirely by his devotion to his employer, and he acts as an obstacle that Haru and Gaku must navigate as they build their own company. There is little documented personal development or change for Nagase throughout the anime; he remains a steadfast, antagonistic presence aligned with the Dragon Bank faction. His notable abilities lie in his physical capability as a bodyguard and his keen observational skills, which allow him to accurately gauge Kirika's unspoken intentions and relay them to others. His appearance and demeanor mark him as a professional and serious figure who prioritizes Kirika's interests above all else.