Tenacity

Tamayo's spirit tells Muzan she never needed raw power to kill him, only the means to weaken him, and that the Corps will do anything to end his life just as he will do anything to preserve his own. Muzan reflects that bright red blades, ordinary Slayer swords, and even regeneration never troubled him, yet the four-part poison has turned trivial attacks into a real threat he will need time to analyze.

When Tanjiro and Obanai move to attack, Muzan releases a shockwave from his body, which has split open into an enormous toothed maw. The blast incapacitates both fighters, sends Tanjiro into a seizure, and even harms the Ubuyashiki children watching from cover. As the demon tries to leave, Inosuke charges in with Beast Breathing's fourth fang to stop him, voicing his grief over the comrades who fell protecting them. Zenitsu then severs the arm about to crush Inosuke, urging Tanjiro to survive and bring Nezuko home.

The chapter continues the second phase against Muzan. The demon attempts to break down Tamayo's poison while Tanjiro and Obanai are stunned by a desperate shockwave attack.

With twenty-five minutes left until dawn, Inosuke and Zenitsu enter the fight to delay the demon, who has worn himself down so far that he can no longer use any technique. Tanjiro deduces that a Blood Demon Art has struck his nerves, and he plunges his Nichirin blade into a spot clear of his organs to halt the convulsions. Sanemi, Giyu, and Gyomei rise from their wounds and start moving to rejoin the battle.

Muzan finds he can barely lift his arms and rages that the Slayers refuse to stay down even when crushed, understanding that they keep rising only to buy time until sunrise.

The Ubuyashiki survivors, blinded to the fight after the talismans are scattered by the blast, can only hope someone keeps the demon from escaping. The chapter is part of the Sunrise Countdown Arc.