Hajime Saitō holds the rank of Captain of the Shinsengumi's 3rd Division. Hailing from Edo, his distinct left-handed swordsmanship grants a tactical edge in combat, uncommon among samurai. Mastery of iai-style techniques and exceptional speed contribute to his reputation as one of the unit's most formidable fighters. Standing 169 centimeters tall, he possesses indigo hair tied in a side ponytail with bangs covering the right side of his face, sharp features, and blue eyes. His standard attire is a black kimono with a white sash and scarf, later replaced by a Western-style black uniform. He wears his sword on the right side to accommodate his left-handed draw. Saitō presents a stoic, reserved, and emotionally controlled demeanor, speaking formally and sparingly. Despite this aloof exterior, he harbors deep loyalty to Shinsengumi leaders Toshizō Hijikata and Isami Kondō, following orders unquestioningly. His analytical nature enables calm situational assessment, enhancing his effectiveness as a spy. He maintains a consistently polite and respectful manner, earning respect even from adversaries. Protective instincts drive his repeated rescues of Chizuru Yukimura, beginning with their first encounter where he saved her from rogue samurai and a failed Rasetsu. He later mentors her in swordsmanship, enabling her patrol participation. His narrative involves significant espionage and combat. He infiltrates Kashitarō Itō’s group as a spy, feigning defection from the Shinsengumi. During this mission, he thwarts an assassination attempt on Kondō and rescues Chizuru from Itō’s forces. Commanding a resistant unit in the Aizu campaign due to his Western attire and left-handedness, he proves his strategic acumen during a siege; his decision to retreat saves lives, winning the unit's respect. At the Battle of Bonari Pass, choosing to remain with the loyal Aizu forces to cover Hijikata’s retreat, he charges the enemy alone. His fate remains ambiguous, implied as death in this battle. Prequel content explores his early Shinsengumi involvement. He joins the Rōshigumi alongside former dojo associates, motivated by loyalty to Kondō and Hijikata. He participates in foundational events, enforcing the group’s Rules of Conduct and demonstrating swordsmanship in a match against Shinpachi Nagakura. His relationship with the demon antagonist Kyūjū Amagiri evolves from rivalry to mutual respect, with Amagiri revealing critical information about the consequences of Rasetsu transformation. The character draws inspiration from the historical samurai Saitō Hajime (1844–1915), who later adopted the name Fujita Gorō and served as a police officer during the Meiji Restoration. While the historical figure survived the Bakumatsu conflicts, his anime counterpart's story concludes during the war.