Giyu Tomioka holds the position of Water Hashira, a top rank in the Demon Slayer Corps. His messy black hair is tied in a low ponytail, contrasting sharp blue eyes and a characteristically stoic expression. He wears the standard black uniform, uniquely complemented by a two-patterned haori: one solid red half, inherited from his late sister Tsutako Tomioka, and the other half featuring a geometric green, orange, and yellow pattern, originally belonging to his deceased friend Sabito. Following the battle against Muzan Kibutsuji, he adopts shorter hair and traditional kimono and hakama pants, having lost his right arm. Born into a fishing family, Giyu endured profound tragedy as his parents succumbed to illness, leaving him in the care of his older sister Tsutako. Demons attacked their home on the eve of her wedding; Tsutako sacrificed herself, barricading Giyu in a room while she was killed. Fleeing, he collapsed on Mount Sagiri and was rescued by Sabito, another trainee under retired Water Hashira Sakonji Urokodaki. During their shared training, Sabito helped Giyu overcome survivor's guilt and despair. Both entered the Final Selection exam, where Sabito perished protecting an injured Giyu from the Hand Demon. Giyu passed by default without killing any demons, deepening his feelings of unworthiness. Emotionally reserved and socially detached, Giyu struggles with a profound inferiority complex rooted in his survivor's guilt. He long believed Sabito deserved the Water Hashira title more and considered abandoning his position, leading to self-imposed isolation from fellow Hashira that some misinterpreted as arrogance. Despite his stoicism, he exhibits fierce loyalty to those he deems worthy. He violates the Demon Slayer Corps' code by sparing Nezuko Kamado after witnessing her defend her brother Tanjiro, later pledging seppuku if she ever harms a human. His guilt begins to subside when Tanjiro reminds him to honor Sabito and Tsutako by valuing his own life. Post-Muzan, he shows greater openness, forming mutual respect with former rivals like Sanemi Shinazugawa and smiling openly. Key development moments include his initial encounter with Tanjiro and Nezuko during a snowstorm. After attempting to kill Nezuko, he spares her upon observing her protectiveness and directs the siblings to Urokodaki, later advocating for their innocence during the Hashira trial. On Mount Natagumo, he effortlessly defeats the Father Spider Demon and Lower Rank Five Rui using his Water Breathing techniques. He physically restrains Shinobu Kocho from pursuing Nezuko, reinforcing his commitment to the Kamado siblings. During the Infinity Castle arc, he battles Upper Rank Three Akaza alongside Tanjiro, awakening his Demon Slayer Mark—a water-like pattern on his left cheek—which enhances his speed and precision. Severely injured, he holds Akaza at bay long enough for Tanjiro to land a decisive blow. In the final confrontation against Muzan, he loses his arm but aids in turning his Nichirin sword crimson to hinder Muzan's regeneration. He later helps contain the demonized Tanjiro until his humanity is restored. As Water Hashira, Giyu masters all ten core Water Breathing forms and develops the unique eleventh technique, Dead Calm, which nullifies incoming attacks. His combat prowess allows him to defeat Lower Ranks effortlessly and contend with Upper Ranks; Akaza acknowledged him as the most skilled Water Hashira encountered in fifty years. His tactical intellect enables him to analyze opponents mid-battle, such as discerning Tanjiro's hatchet strategy or Akaza's combat adaptation. He also demonstrates survival ingenuity, cauterizing wounds post-battle. Retiring from demon slaying after the war, he continues mentoring new recruits.