Sakonji Urokodaki, a retired Demon Slayer and former Water Hashira, dedicates his post-combat life to mentoring future warriors in the art of Water Breathing. His face remains hidden beneath a red tengu mask, initially worn to shield his kind expression from demonic ridicule—a truth uncovered by his student Tanjiro Kamado through a Taisho-era secret. The mask also honors his role as a mountain guardian, echoing tengu legends of protection. Clad in a cloud-patterned jinbei, navy trousers, and white leg wraps, he embodies practicality veiled in mystery. A stern yet devoted teacher, Urokodaki devises grueling trials—trapped obstacle courses, endurance tests, and the near-impossible task of cleaving a giant boulder—to forge resilience in pupils like Tanjiro. His severity roots in grief: thirteen prior trainees fell to the Hand Demon, a vengeful entity he once captured and confined on Mount Fujikasane. This loss drives his merciless standards, though his compassion surfaces when survivors like Tanjiro return, met with tearful embraces and quiet pride. Beyond combat drills, Urokodaki crafts fox masks to safeguard students, unaware these symbols would mark them as the Hand Demon’s prey. He engineers a sunlight-resistant box from Mist Cloud Fir wood to shield Tanjiro’s demon-turned sister, Nezuko, and hypnotizes her during recovery to suppress her bloodlust, staking his life as forfeit should she harm humans. His faith in her humanity compels him to lobby the Demon Slayer Corps for her acceptance, vowing shared demise with Tanjiro and Giyu Tomioka if she falters. Master of all ten Water Breathing forms, Urokodaki wields fluid strikes and breath control to amplify strength, once overpowering the Hand Demon alone—a testament to his tactical brilliance. Even retired, his stealth, speed, and acute scent detection persist, skills he hones in Tanjiro to track foes and decipher battlefields through scent. During Muzan Kibutsuji’s final assault, Urokodaki stands guard as Nezuko undergoes Tamayo’s experimental cure, thwarting Muzan’s pursuit of her immunity. Post-victory, he aids survivors, upholding his lifelong pledge to nurture those under his care. His legacy endures through resilient protégés, inventive training regimens, and an unshakable conviction in his students’ capacity to transcend darkness.