Demon Slayer Chapter 129

Demon Slayer Chapter 129, titled "To Become a Marked One," delves into the mysterious criteria for manifesting the coveted Demon Slayer Mark, setting the stage for the rigorous Hashira Training Arc, while Tanjiro Kamado receives his long-awaited, fully restored Nichirin Sword. The chapter opens with Muichiro Tokito explaining his experience during his recent fight: he was paralyzed by poison, and his breathing techniques allowed him to slow its circulation. A boy attempting to save him was almost killed, which, coupled with the dire situation, triggered the return of his lost memories. Lost in his anger and desperation, he believes his heart rate must have exceeded 200 beats per minute, and his body temperature rose above 39°C. Shinobu Kocho is surprised, deeming such conditions potentially fatal. Muichiro posits that surviving these harsh physiological conditions is what separates those who can manifest the mark from those who cannot. Amane Ubuyashiki asks how he determined his body temperature, to which he recalls experiencing a fever of that intensity, feeling the same sensation when the mark appeared, offering a crucial clue to the Hashira.

Sanemi Shinazugawa expresses surprise at the seeming simplicity of these conditions, prompting Giyu Tomioka to comment on Sanemi's "simple mind" for believing such straightforward criteria. Giyu, however, does not elaborate when confronted by the Wind Hashira. Shinobu believes all the Hashira must strive to attain the mark, and Gyomei Himejima concurs, asking Amane to ease Kagaya Ubuyashiki's concerns. Amane, however, adds a sobering caveat: for those who have already manifested the mark, it is too late; an unavoidable fate awaits them, casting a dark shadow over their newfound power. After Amane leaves, Giyu excuses himself, prompting Sanemi to confront him for attempting to leave. Giyu states that the six of them should talk, pointedly excluding himself. Obanai Iguro questions Giyu's remarks, wondering if he's not taking his Hashira duties seriously or if he intends to train ahead of them. As Giyu walks away, Sanemi angrily yells at him to stop, and Shinobu asks him to explain himself. Giyu simply claims he is "different" from them, infuriating Sanemi, who has heard the phrase before and angrily asks if Giyu looks down on them. Mitsuri nervously steps between them to prevent a fight, but the tension is diffused by a loud clap from Gyomei, who orders them to sit down and explains he has a proposal.

At the Butterfly Mansion, Hotaru Haganezuka arrives to deliver Tanjiro his sword. The swordsmith is visibly exhausted, breathing heavily, with sweat beading on his mask. Hotaru gives Tanjiro his sword and, at Goto's request, sits down. Tanjiro is amazed to see Kyojuro Rengoku's tsuba on his new blade. The swordsmith urges Tanjiro to unsheathe it, and Tanjiro is in awe of its appearance. Hotaru explains that because it's made from high-quality steel, it must have been previously wielded by a strong swordsman. He points out the single kanji for "Slay" (滅, Metsu) carved on the blade, explaining that such blades were forged before the Demon Slayer rankings were established, which is why only the Hashira have the full phrase "Destroyer of Demons" (惡鬼滅殺, Akki Messatsu) on their swords. When Tanjiro asks why he couldn't see the kanji before, Hotaru angrily retorts that it was only polished to its first stage when Tanjiro last used it. Even now, the pain of polishing it hasn't subsided, hence his exhausted state, and he adds that he was repeatedly interrupted, playfully pulling Tanjiro's cheek. Goto interjects, explaining that Tanjiro's own wounds are as severe as Hotaru's to defuse the situation. Hotaru turns to Goto, playfully threatening the Kakushi, then demands a lifetime supply of mitarashi dango from Tanjiro, to which Tanjiro readily agrees, bidding the swordsmith farewell as he leaves. Goto asks about rumors of Hotaru's temper, and Tanjiro remarks that, considering his pain, Hotaru was actually calm today. Lying in the bed beside him, an annoyed Genya asks Tanjiro why he's being noisy. Tanjiro attempts to apologize but is interrupted when Inosuke Hashibira crashes through the window. Goto and Tanjiro reprimand Inosuke as Genya wishes he were elsewhere, while Inosuke announces that training to get stronger has begun. When Tanjiro asks for details, Inosuke replies he doesn't know, ending the chapter on a lighthearted note amidst the serious preparations for the upcoming Hashira Training Arc in the Demon Slayer manga.