After crossing paths with Muzan, Yoriichi immediately senses his violent intent, comparing it to "magma erupting from a volcano."Muzan instigates the confrontation by stating his disinterest in swordsmen that utilize breathing techniques. Shortly after, he unleashes his arms and outright attempts to kill him. Though Yoriichi dodges the attack, he knew then that even a single strike will be fatal.
By seeing to the Transparent World , Yoriichi was able to discern that Muzan had a total of seven hearts and five brains. Despite the Demon Lord's own immense power, Yoriichi manages to complete his sword forms and combine them into a single attack, overpowering Muzan completely. As Tanjiro, through Sumiyoshi, listens to the story, he realises he had created the 13th and final form of Sun Breathing.
Despite trying to regenerate his body, Muzan becomes stunned and is forced to hold his head in place to keep it from falling off. Yoriichi realizes that the immense amount of damage was caused by the bright red blade that the wielded. He questions Muzan on what he believes of the value of life, only to receive a furious glare as an answer.
Believing his words didn't reach him, Yoriichi's attention is then drawn to the young Demon girl travelling with Muzan. He immediately notices her eyes staring directly at Muzan, not with a look of concern, but with a look of hope as he sat there dismembered and holding his severed head.
Before he began dealing with her, Yoriichi approaches Muzan in order to finish him off. However as he walked towards him, the sounds of teeth grinding grew louder until Muzan's body bursts into many small pieces. Caught off-guard, Yoriichi was only able to cut 1,500 of the 1,800 total bits of flesh, leading the remaining portions to regenerate elsewhere and escape.
The girl collapses on the floor and begins to weep while tearing out her hair, angrily cursing that Muzan should had died. She is then surprised that she managed to survive despite saying Muzan's name out loud. Yoriichi approaches her and calms her down before she eagerly informs him about Muzan, how he was the progenitor of Demons and would most likely never appear before Yoriichi again. He asks for her compliance in defeating Muzan, to which she agrees, and allows her to escape. She introduces herself as Tamayo to Yoriichi, something Tanjiro is surprised at.
After his interactions with the Demons, Yoriichi is approached by the other Demon Slayers whom inform him that his brother, Michikatsu, had become a Demon. Once they return to the estate, he is angrily confronted by the rest of the swordsmen for failing to kill Muzan, for letting Tamayo escape and for Michikatsu's transformation into a demon. As a result, he was banished from the Demon Slayer Corps and was demanded to commit seppuku, but the newly assigned Oyakata would not allow it to happen.
After telling Sumiyoshi the end of his story, Yoriichi reveals his thoughts of being born with the gift to defeat Muzan but his failure to do so, and that because of his mistake, many more people would begin to perish at the hands of Muzan, telling him it pains him.
Distraught by his inability to comfort his friend for going through so much, Sumiyoshi sits beside Yoriichi in silence until Sumire slowly walks towards the swordsman. She tugs softly on his clothes and says "Hug!". Surprised by the child's sudden demand, Sumiyoshi asks if his guest would mind carrying her to make her happy. Without a response, Yoriichi picks up the little girl and lifts her up into the air.
The little girl squeals with delight and happiness, causing Yoriichi to emotionally break down and his eyes to fill with tears. Soon after, Suyako returns from gathering chestnuts in the forest and discovers Yoriichi weeping as he hugs the little girl.
Suyako comes forth to comfort Yoriichi saying she'll treat him to a warm meal. the chapter concludes with Tanjiro wishing Yoriichi's heart to find any form of peace after hearing everything he went through.
Characters in Order of Appearance
- More is learned about Yoriichi's past.