The world, a tapestry woven with threads of peril, offered little solace to Giyu and his elder sister, Tsutako. Orphaned by fate's cruel hand, their fragile existence was shattered by the descent of a demon, a creature of nightmare intent on extinguishing their nascent light. In a moment of breathtaking courage, Tsutako surrendered her life, her final act a desperate gamble to conceal Giyu, to shield him from the encroaching darkness. The townsfolk, unable to fathom such monstrous reality, deemed him unhinged and consigned him to the care of a distant relative. Yet, Giyu’s spirit, though battered, remained unbroken. During the arduous journey, he seized an opportunity, slipping away into the unforgiving wilderness. Found near death, he was discovered by the enigmatic Sakonji Urokodaki, who offered him sanctuary and began the arduous path of transforming him into a formidable Demon Slayer. Within Urokodaki’s tutelage, Giyu forged a profound bond with Sabito, their friendship blossoming amidst the crucible of their training. This nascent camaraderie was brutally tested during the Final Selection. Incapacitated by the grotesque Hands Demon, Giyu could only witness the ensuing battle from afar as Sabito and Makomo confronted the monstrous entity. Hours later, victory was declared, though it was a hollow triumph. The Hands Demon had escaped, In the aftermath, Sabito was bestowed the esteemed rank of Water Hashira, while Makomo embraced a role as mentor. Giyu, his resolve hardened, remained steadfast by Sabito's side, their training intensifying. It was during this period that Giyu unveiled the Eleventh Form of Water Breathing, a technique he christened "Dead Calm."

Years later, traversing snow-laden mountains, Giyu’s path intersected with a boy bearing blood-red flame-like markings on his forehead, accompanied by his demon sister. Instinct took hold, and Giyu launched an immediate assault, intent on vanquishing the fiend. However, the boy, displaying remarkable skill despite his apparent lack of training, fiercely protected his sibling. Giyu, witnessing the unwavering bond between them, made a fateful decision. He dispatched them to Sakonji Urokodaki and Makomo, with a stern warning to keep the sister away from sunlight. For two years, Tanjiro dedicated himself to rigorous training, ultimately triumphing in the Final Selection and slaying the Hands Demon. Time marched on, and Giyu soon learned of Sabito and Shinobu embarking on a mission alongside Kanao. He stealthily joined their ranks, arriving precisely as Tanjiro engaged in a valiant battle against the demon Rui. Urgently, Giyu warned the boy to flee before his companions could intervene, leaving Tanjiro to navigate the ensuing complexities with Shinobu. Subsequently, Sabito and Shinobu escorted a weary Giyu back to the Hashira Headquarters, where the Hashira Meeting commenced, the air thick with discussions concerning Tanjiro, Nezuko, and Giyu. The atmosphere transformed with the arrival of Kagaya Ubuyashiki, whose words painted a vivid picture of Tanjiro’s astonishing victory over the lower moon demon, Rui. The revelation of Tanjiro's nascent Demon Slayer mark, a legendary birthright, catapulted him into the esteemed ranks of the Sun Hashira. And he fought formidable adversaries such as Akaza, Daki, Gyutaro, Hantengu, and Gyokko. Meanwhile, Nezuko, his demonic sister, began her own subtle ascent, gradually reclaiming her human consciousness and voice. Her demonic form evolved, becoming a vessel for her burgeoning powers as a slayer. Yet, the ever-present shadow of Muzan cast a dark pall over their victories, his relentless pursuit of Nezuko igniting a fierce urgency within the Hashira, compelling them to elevate their rigorous training to unprecedented heights. In the present day, Giyu found a rare moment of solace, leaning against the sturdy trunk of a tree. The gentle rustle of leaves enveloped him as he softly closed his eyes, surrendering to the calming embrace of nature, seeking a brief respite from the ceaseless chaos of the world.