Sakonji Urokodaki

Sakonji Urokodaki (鱗滝 左近次 Urokodaki Sakonji) is the former Pilar (Hashira) of Water; he is introduced to Tanjiro and Nezuko by his student Giyu Tomioka. He is initially worried by Tanjiro's kind nature, but agrees to train him. As the training progresses, he grows closer to Tanjiro and Nezuko, and sheds tears of joy, when Tanjiro returns alive from the Final Selection, as he is the first after several years to do so since Tomioka's time, in addition to breaking a long series of deaths involving several of his disciples. Since then, he has closely monitored Tanjiro's growth as a member of the Demons Slayers corps, as well as Nezuko's status as a demon throughout the series. He has also given his word to the Pillars (Hashiras) and the leader of the Demons Slayers guild that if Nezuko one day were to devour a human, he, as well as Tanjiro and Giyu, would be in charge of killing her and then they would kill her. They would commit suicide through the Seppuku ritual.