Two years later, Tanjiro learns the "Water Breathing" style and takes part in a formidable exam. He is one of the few to pass, officially making him a member of the Corps. Sakonji has hypnotized Nezuko to not harm humans and she aids Tanjiro in dire situations as he starts his work of hunting down and slaying demons. One of their assignments bring them to Asakusa where they encounter Muzan Kibutsuji, the progenitor of all demons and the one responsible for the murder of their family. Tanjiro and Nezuko also meet Tamayo and Yushiro, two demons free from Muzan's control. They ally to develop a cure for Nezuko, though it will require Tanjiro to supply Tamayo with blood samples from the Twelve Kizuki, the twelve most powerful demons under Muzan's command, split into the six Lower Ranks and the six Upper Ranks.