Demon Slayer: Kimetsu no Yaiba Episode 26: New Mission

Tanjiro continues his intense rehabilitation training at the Butterfly Mansion, steadily improving his skills until he can match Kanao evenly in games of tag and reflex challenges, even catching her off guard. He also masters Total Concentration Breathing at all times, including while asleep, with help from Naho, Kiyo, and Sumi, who tie him up at night to maintain his form.

Meanwhile, in a disorienting, twisting maze of corridors and stairways, the five remaining Lower Rank demons of the Twelve Kizuki are summoned by a mysterious woman with a menacing presence. She reveals herself as Muzan Kibutsuji, the demons' absolute master, who berates them for their repeated failures against the Hashira and the Demon Slayer with hanafuda earrings, especially after Lower Five's defeat.

Muzan kills Lower Three with his monstrous arm after the demon fears execution despite his efforts. He then crushes and absorbs Lower Four, accusing her of fearing Hashira more than him and only thinking of fleeing. The other Lower Ranks meet quick, gruesome ends as they beg, flee, or argue, reduced to gore and puddles.

Only Lower One survives, eagerly welcoming death and thanking Muzan for letting him hear the tortured screams of the others, as he loves such sounds. Impressed, Muzan injects him with a massive amount of his blood, causing agonizing convulsions but granting immense power if he endures. Muzan tasks him with killing a Hashira and the hanafuda earring-wearing Demon Slayer to earn more blood.

Training complete, Tanjiro and his companions bid farewell to the Butterfly Mansion girls, destroying multiple iron gourds to prove their constant breathing mastery. Giyu Tomioka appears, commends their progress, and urges Tanjiro to thank him by killing demons, as Tanjiro expresses gratitude for Giyu's past aid with Nezuko.

Tanjiro's Kasugai Crow arrives with a new mission: head to the Infinite Train where Rengoku awaits. The episode closes with a sweeping shot of the train carrying Rengoku, unaware that the empowered Lower One demon lurks on its roof.