The real world.
At the very moment Muzan's lingering echo was completely purified in the Mental World, Demon King Tanjiro, pinned down firmly by the Hashira on the battlefield, suddenly went rigid.
His frenzied struggles stopped abruptly.
The towering, suffocating demon aura rapidly dwindled and dissipated like a punctured balloon.
Everyone stared at this sudden change in astonishment.
"Did it work?" Kyojuro Rengoku panted, barely able to hold his sword.
Visible changes were taking place in Tanjiro's body.
The hideous bone whips on his back, replicas of Muzan's, lost the power sustaining them. They softened and shriveled one after another, finally turning into pools of foul-smelling blood that dripped onto the ground.
The color in his demon eye, with its slit pupil and ominous gleam, was rapidly fading, changing little by little back to its original, gentle, dark red human hue.
The Demon King's curse binding him was being dismantled from within!
"The medicine! The medicine!"
Zenitsu suddenly remembered something. Scrambling through the rubble on his hands and knees, he finally found the syringe filled with Demon Transformation Medicine that Kanao had accidentally dropped.
This was the final fruit of Miss Tamayo's and Miss Shinobu Kocho's painstaking work!
With trembling hands, he passed the syringe to Kanao, who was closest to Tanjiro.
Kanao could barely see anything anymore. Relying on what remained of her sense of touch and her memory, she fumbled for the syringe and took it. She could feel that although Tanjiro's body was no longer giving off demon aura, his vitality was also draining away at an alarming rate.
His earlier forced transformation into the Demon King had already exhausted all the life he possessed as a human. If the medicine did not turn him completely back in time, he would certainly die even with Muzan's will