Giyu Tomioka holds the position of Water Hashira in the Demon Slayer Corps. His past is defined by profound loss, starting with his older sister Tsutako sacrificing herself to a demon on her wedding day to save him, which motivated him to become a Demon Slayer. He trained under Sakonji Urokodaki alongside Sabito and Makomo. Sabito died protecting others during the Final Selection while Giyu survived, instilling deep survivor's guilt that shaped his self-perception. Giyu wears a combined haori made from Tsutako's red haori and Sabito's geometrically patterned one as a memento. Giyu maintains a stoic and reserved exterior, often perceived as aloof by Hashira like Sanemi Shinazugawa and Obanai Iguro. This stems from difficulty with social interaction and an inferiority complex, believing Sabito deserved his title more. He rarely speaks at length, explicitly disliking unnecessary conversation, especially with demons. Despite this, he possesses a strong sense of justice and pragmatism. He spares Nezuko Kamado after witnessing her protect her brother Tanjiro, violating protocol to vouch for her with his life—pledging seppuku if she harmed humans. He later defends her against Shinobu Kocho's attacks, judging demons individually. Beneath his restraint lies significant survivor's guilt and self-doubt. He initially declines to join Hashira Training, feeling unworthy and contemplating resignation. Tanjiro Kamado helps him reframe this guilt into resolve to honor the fallen. Giyu's protective instincts emerge strongly for those he values: he fiercely intervenes when Akaza targets Tanjiro and shows visible shock at Shinobu's death, though he displays little reaction to the deaths of Genya Shinazugawa or Muichiro Tokito. In combat, Giyu masters Water Breathing, utilizing all ten standard forms and developing the unique eleventh technique *Dead Calm* (拾壱ノ型 凪, *Jūichi no Kata: Nagi*), which nullifies attacks. He demonstrates exceptional speed and tactical intellect, effortlessly defeating Lower Rank Five Rui and the transformed Father Spider Demon. Against Upper Rank Three Akaza, he awakens his Demon Slayer Mark—a water-like pattern on his left cheek—significantly enhancing his speed and endurance, earning Akaza's acknowledgment as the most skilled Water Hashira in fifty years. During the final conflict against Muzan Kibutsuji, Giyu loses his right arm and temporarily wields a Crimson Red Nichirin Sword to impede Muzan's regeneration. He later confronts a demonized Tanjiro, holding him off until Tanjiro's humanity returns. Following Muzan's defeat and the end of the demon threat, Giyu undergoes subtle development. He cuts his hair to neck length and adopts simpler clothing, symbolizing a release from past burdens. His relationships with survivors like Sanemi and Tengen Uzui evolve into mutual respect. He begins to smile openly, reflecting a newfound ability to embrace life without the weight of guilt, particularly in interactions with the Kamado siblings.