Demon Slayer Chapter 138

Demon Slayer Chapter 138, titled "An Unexpected Ally," propels the narrative into the climactic Infinity Castle Arc, as Kagaya Ubuyashiki executes a daring, suicidal plan to finally confront Muzan Kibutsuji, aided by a shocking deception from Tamayo. The chapter opens with Muzan, poised to strike, his claws extended towards Kagaya. Kagaya, maintaining a serene demeanor, acknowledges that he has indeed finished speaking. He then reveals that he will not kill himself—a statement that briefly confuses Muzan. Just as Muzan attempts to attack, a massive explosion rips through the mansion, engulfing both Kagaya and Muzan in flames. The Oyakata, along with his wife Amane, and their two daughters, Nichika and Hinaki, have orchestrated a devastating suicide attack, using explosives hidden within their home to inflict damage upon Muzan. The Demon King is momentarily caught off guard, experiencing immense pain and confusion as his body is ripped apart by the blast.

Simultaneously, a new threat emerges. Muzan, in his agony, feels a strange presence on his back, realizing a woman is clinging to him. He recognizes her—Tamayo, the demon doctor who betrayed him centuries ago. Tamayo, with an unwavering look of hatred, states that she will never forgive him. As the dust settles, Muzan, still regenerating, sees the entire Ubuyashiki mansion destroyed, with Kagaya's body lying among the rubble. He immediately realizes Kagaya had sacrificed himself to create an opening for Tamayo to administer a special drug, designed to weaken him. Muzan, enraged, demands to know the purpose of the drug, but Tamayo calmly explains that it is a four-stage formula, designed to transform him into a human. She reveals that she has been working on this antidote for centuries, using her vast knowledge of demon physiology and Muzan's own blood to create a potent weapon against him. This shocking revelation underscores Tamayo's long-standing vendetta and her crucial role in the Demon Slayer Corps' ultimate plan.

Muzan attempts to kill Tamayo, but she skillfully dodges his attacks, protected by her Blood Demon Art: Magical Aroma of Daylight. This technique distorts the demon's perception, making her movements unpredictable and her presence elusive. As the battle intensifies, Tamayo reveals that she has also developed a poison that can rapidly age Muzan, accelerating his demise. Muzan, now fully aware of the extent of Tamayo's betrayal, is consumed by a furious rage. He realizes the Demon Slayer Corps has been working in secret with Tamayo, meticulously planning his downfall for years. The chapter concludes with Muzan trapped in a desperate struggle against Tamayo's cunning strategies and potent concoctions, while the Hashira and other Demon Slayers, alerted by the explosion, prepare to enter the fray, signaling the true beginning of the Infinity Castle Arc and the final battle against the Demon King in the thrilling narrative of the Demon Slayer manga.