Female. Late 20s. An enthusiastic, newly appointed Customs officer. Although GATE 24 is her first field assignment, she deciphers the truth from physical objects with her overwhelming powers of observation. She possesses an astonishingly wide range of knowledge. When she focuses too intensely, she tends to forget rules and regulations, becoming oblivious to the voices around her.

Male. Late 20s. An Immigration officer. A career bureaucrat from the Ministry of Justice and a candidate for executive leadership. He volunteered for GATE 24 to gain field experience. An elite professional who pierces through to the truth of individuals based on law and data. He never causes trouble. While highly skilled in communication, it is largely a survival tactic to avoid making waves within the organization.

Male. Early 20s. A promising young talent who worked his way up to become a Customs officer after graduating high school. He takes great pride in Customs being the nation's final line of defense and carries out his duties with meticulous care. Though he can be stubborn and inflexible, leading to occasional clashes with the elite bureaucrat Hayami, his kind nature and the advice of trusted superiors—combined with his meeting Machi—help him grow into an excellent Customs officer.

Female. Mid-20s. A national civil servant belonging to the Animal Quarantine Service of the Ministry of Agriculture, Forestry and Fisheries. After graduating from veterinary school and obtaining her license, she became an animal quarantine officer. A modern young woman. While she can be hard to read, her work speed is astonishing. With calm judgment and high practical ability, she serves as the unsung hero of GATE 24.

Female. Late 20s. Ground staff. Machi's classmate and best friend. Possessing a straightforward personality that hates lies, she is a great supporter and understanding friend to the eccentric and quirky Machi. She supports the GATE 24 team from the public stage of the airport lobby.

Male. Late 30s. A Supervising Examiner. Although he serves as the leader of GATE 24, he is an unreliable middle manager who seeks Hayami or Fukasawa's judgment at every turn. He is the type to go with the flow and is unnervingly deferential toward the elite Hayami. He has a gentle personality.

Male. Early 60s. Chief Inspector of the Kanto Regional Immigration Bureau. Resonating with Midori's philosophy, he was invited to GATE 24 near his retirement. Calm and soft-spoken, he is a kind, father-like figure to the team. He fully understands the weight of making judgments without harboring illusions about human goodwill or malice. He supports the team with all his might.

Female. Early 50s. Councilor of the Cabinet Secretariat Border Management Reform Office. An elite bureaucrat belonging to the Cabinet Secretariat and the creator of this project, who proposed GATE 24 to break down administrative silos. She bets everything on GATE 24, trusting the members like Fukasawa whom she personally appointed. She trusts Fukasawa, who once taught her the ropes of field work with great care. She maintains her own information networks outside of official channels, such as foreign authorities and international organizations.

Male. Early 60s. A detective belonging to the International Crime Division of the Tokyo Metropolitan Police Department. He upholds a logic of investigation that allows criminals to enter the country if it leads to the eradication of evil organizations. He frequently clashes with GATE 24, which enforces strict border measures, but will cooperate on investigations when necessary. He is blunt but can be reliable at times.

Male. Early 30s. A detective in the International Crime Division of the Tokyo Metropolitan Police Department and Inouchi's loyal subordinate and partner. He has a strong sense of justice and is calm and collected. Carrying his pride as a police officer, he monitors the movements of GATE 24, with whom he frequently conflicts.