After a desperate fight to the death, Tanjiro prevails over Kyogai. He exits the house to find Zenitsu who had escaped earlier. But it is then that he sees the strange circumstances before him... The battered Zenitsu holding the box containing Nezuko in his arms while the man in the boar's head mask stands in the way with two Nichirin Swords drawn.

One of the Twelve Kizuki, a direct subordinate of Muzan Kibutsuji, is here somewhere. When Tanjiro slays the Mother Spider Demon of Mt. Natagumo, he learns that a demon who might hold the key to turning Nezuko back into a human is somewhere in this very forest. With the battered Inosuke in tow, he heads deeper into the forest. Meanwhile, Zenitsu trudges forlornly through the woods only to encounter a spider with a human face.

Ubuyashiki, the leader of the Demon Slayer Corps, finally appears before Tanjiro. He tells him that he will allow Tanjiro and Nezuko to join the Corps. But the Hashiras are unable to accept this decision right away. The Wind Hashira, Sanemi Shinazugawa, slashes his own arm and taunts Nezuko with his blood, trying to get her to show her true colors as a demon.

Tanjiro, who's undergoing rehabilitation training at the Butterfly Mansion, works hard to keep up his Total Concentration Breathing techniques all day long. Though at first, he's helpless against Kanao, a swordswoman in his class who's training him, he slowly but surely begins to make some headway. Seeing Tanjiro devote himself to training every single day, Zenitsu and Inosuke resume training as well, but...