Soji Okita serves as captain of the Shinsengumi's 1st Division, renowned as the group's strongest swordsman and earning the epithet "The Sword of the Shinsengumi." His exceptional swordsmanship was forged through rigorous training alongside Isami Kondou and Toshizou Hijikata at the Shieikan dojo from a young age. Standing averaging around 177 cm tall, he has chestnut brown hair typically worn in a topknot and emerald green eyes. His standard attire consists of a red, gray, and orange haori over green hakama with white kyahan leg wraps. Following his tuberculosis diagnosis, he is frequently seen in a white sleeping robe due to enforced rest. Later, he adopts Western-style clothing in a similar palette of red, orange, green, and black. He exhibits a charming yet sarcastic and occasionally sadistic demeanor, frequently taunting other Shinsengumi members—particularly Hijikata. He openly threatens to kill Chizuru Yukimura if she obstructs missions or learns sensitive information, though he repeatedly protects her in practice. Despite his abrasive exterior, he harbors profound loyalty, especially toward Kondou, whom he idolizes and emulates, adopting Kondou's hairstyle. He often withholds information to observe reactions, exemplified by concealing Chizuru's gender despite finding it "obvious." Orphaned at seven, he was raised by his sister until she left him at Shieikan at nine. Kondou took him under his wing, though Souji endured severe bullying from older students, leading to deep-seated emotional detachment. This childhood trauma fostered a belief that self-worth stemmed solely from utility to Kondou, causing jealousy toward Hijikata for Kondou's attention. His moral compass became distorted; he perceived killing as justified if it served Kondou's goals and envied comrades who had killed in battle. His relationship with Chizuru evolves significantly. Initially indifferent, he views protecting her as an obligation to Kondou. Over time, her treatment of him as an equal—rather than a weapon—gradually lowers his emotional barriers. His dynamic with Hajime Saitou is defined by mutual respect and unspoken understanding, contrasting with his volatile exchanges with Hijikata, whom he nonetheless acknowledges as a brother. During a confrontation with the demon Kazama Chikage, he begins coughing blood and receives a tuberculosis diagnosis. His health deteriorates, confining him to bed. Despite this, he participates in critical battles, including avenging Kondou's capture and death. In one instance, he consumes the Ochimizu (Water of Life) to become a Rasetsu (Fury), enhancing his combat abilities at the cost of accelerated physical decay. After Kondou's execution, he initially confronts Hijikata in rage but stands down upon learning of Hijikata's injuries. In his culminating act, he defends a wounded Hijikata from assassins by entering Rasetsu form. He single-handedly eliminates the attackers but exhausts his life force, disintegrating into dust and leaving only his sword behind. Alternate portrayals show him succumbing to tuberculosis after killing Chizuru's brother, Kaoru Nagumo, during the Shinsengumi's retreat.