Demon Slayer Chapter 166

Demon Slayer Chapter 166, titled "True Feelings," deepens the intense battle against Upper Rank One, Kokushibo, as Sanemi Shinazugawa makes a dramatic entrance to save his brother Genya, revealing the raw and complex emotions beneath their strained relationship. Kokushibo stands before Muichiro Tokito, who is pinned by his own katana, expressing a rare flicker of emotion at seeing his descendant, and promises Muichiro's arm will regenerate if he becomes a demon. He muses that he is now the only remaining Upper Rank able to fight, and that Muzan would welcome Muichiro. Kokushibo then gently tends to Muichiro's arm stump, deeming humans fragile, yet asserting that if Muichiro bleeds to death or Muzan rejects him, it's his inevitable human fate in the thrilling narrative of the Demon Slayer manga.

Genya Shinazugawa, having entered the room, hides behind a wall as Kokushibo attends to Muichiro. He fires his shotgun, but Kokushibo instantly appears behind him, questioning if he agrees with his sentiment. Genya's left arm is severed, paralyzed by fear. Muichiro screams his name as Genya attempts to draw his wakizashi, but his right arm also flies off, severed with such speed that Kokushibo appeared not to move. Upper One observes Genya's demon-eating ability, then slashes his torso. Muichiro frantically tries to free himself, unable to pull out the katana. Kokushibo, reminiscing about a similar demon-eating Demon Slayer 300 years prior, who he also decapitated, declares he has no reason to allow an "imitation demon" like Genya to live. Genya desperately crawls towards his severed arm as Kokushibo prepares a finishing blow.

However, Sanemi Shinazugawa dramatically arrives, using Wind Breathing, Fourth Form: Rising Dust Storm, to push Kokushibo away from Genya. Kokushibo faces the Wind Hashira, who boldly asserts, "That's right! And that wind... is gonna wrench your head off!" Genya is shocked to see his older brother, who calls him a pathetic sibling before revealing his true motivation for killing their mother: to protect Genya. This revelation stirs Genya's memory of a conversation with Tanjiro, who noted Sanemi's underlying love despite his harsh exterior. Sanemi then shares his dream for Genya: a home, a family, and old age, to compensate for their lost mother and siblings. "And I would've never let a demon near you." As Genya tearfully apologizes, Kokushibo remarks on the nostalgic sight of brothers as Demon Slayers. Enraged by Genya's maiming, Sanemi charges at Kokushibo. Upper One slashes at him, but Sanemi ducks, slides between his legs, and attempts to catch his foot. Kokushibo leaps up, but Sanemi responds with Wind Breathing, First Form: Dust Whirlwind Cutter, forcing a blade clash as Kokushibo lands. Muichiro notices Kokushibo's drawn katana is grotesque, covered in numerous twitching eyes, foreshadowing the horrifying extent of his demonic transformation and the brutal fight to come in the climactic Infinity Castle Arc of the Demon Slayer manga.