Ep. 15: Zenitsu follows Tanjiro to Mount Natagumo where demon slayers are controlled by spider threads.
After recovering, Tanjiro, Zenitsu, and Inosuke travel to Mount Natagumo. Zenitsu, harboring a crush on Nezuko, reluctantly follows Tanjiro after being left behind. They encounter a wounded slayer dragged away by threads and meet Murata, who reveals ten slayers turned on each other. Meanwhile, the commander sends Hashira Tomioka Giyū and Shinobu as backup. Zenitsu finally advances, realizing Tanjiro entered the mountain. Captured slayers emerge as puppets, but Tanjiro stops Inosuke from attacking the living ones. Inosuke frees them, prompting the Spider Mother to send spiders to reattach the strings. A white-haired demon boy named Rui appears, claiming his family will live happily, while Inosuke uses Spiritual Awareness to locate the Mother.
Episodes
- Ep. 11 · Tanjiro and Zenitsu enter the shifting Tsuzumi Mansion to confront a demon controlling the house.
- Ep. 12 · Inosuke attacks Tanjiro while Zenitsu unknowingly defeats a demon during sleep
- Ep. 13 · Tanjiro defeats Kyogai and confronts a rogue slayer protecting Nezuko's box
- Ep. 14 · The House with the Wisteria Family Crest
- Ep. 15 · Zenitsu follows Tanjiro to Mount Natagumo where demon slayers are controlled by spider threads.
- Ep. 16 · Tanjiro and Inosuke face controlled slayers and a headless demon doll while Mother meets her end.
- Ep. 17 · A subordinate of Muzan Kibutsuji is nearby after Tanjiro defeats the Mother Spider Demon
- Ep. 18 · Giyu and Shinobu arrive at Mount Natagumo while Tanjiro and Inosuke battle Father and Rui.
- Ep. 19 · Water Hashira Giyu Tomioka defeats the Father Spider Demon on Mt. Natagumo