Chapter Summaries

On the Infinite Train, Rengoku Kyojuro declared that Riezel would become his Successor Disciple, though Riezel denied agreeing to it and revealed he was an unrelated civilian. After the conductor checked everyone’s tickets, Riezel realized too late that the demon’s hypnosis might affect him despite his mental defenses.

• Tanjiro told Rengoku Kyojuro that he believed Nezuko would earn his recognition, while Rengoku said he would observe them.
• Rengoku Kyojuro announced that Riezel would become his Successor Disciple, but Riezel clarified that they had only met on the train and Rengoku had not asked his consent.
• Zenitsu worried that the Demon Slayer Corps had brought an unrelated civilian into the mission, while Riezel said he could protect himself.
• Inosuke, Tanjiro, and Zenitsu each sensed that Riezel was unusually strong, and Riezel recognized their exceptional senses of touch, smell, and hearing.
• The conductor checked and punched the passengers’ tickets, which Riezel knew had been tampered with to trigger the demon’s hypnosis.
• Riezel let the conductor punch his ticket, assuming his mental defenses would protect him, as Tanjiro’s Nichirin Earring chimed.

Riezel was drawn into a dreamscape where an unknown swordsman demonstrated Sun Breathing and passed its forms to him. The swordsman left Riezel with the task of carrying on before the dream faded.

• Riezel realized he was on a mountain inside the Infinite Train demon’s dreamscape and prepared to kill himself to wake up.
• A swordsman wearing Sunflower Paper Earrings told Riezel that Sun Breathing had thirteen forms and began demonstrating the technique.
• The swordsman performed twelve forms repeatedly while Riezel watched and unconsciously synchronized his breathing with him.
• Riezel absorbed the swordsman’s breathing and sword forms as his own power grew stronger, though the thirteenth form was never shown.
• The swordsman told Riezel, “I’ll leave it to you,” before his earrings rang and Riezel’s consciousness faded.

Riezel awoke aboard the demon-fused Infinite Train and joined Rengoku Kyojuro in protecting its passengers from the demon's tentacles. He left to stop the train so Rengoku could evacuate everyone, while Tanjiro and Inosuke ran along the roof and spotted someone bursting through the train wall.

• Rengoku Kyojuro explained that the demon had trapped the passengers in dreams using blood-tainted tickets and fused itself with the train.
• Riezel and Rengoku Kyojuro cut down tentacles threatening the sleeping passengers across several carriages.
• Riezel proposed stopping the train so Rengoku Kyojuro could move the passengers to safety, then vanished to carry out the plan.
• Tanjiro and Inosuke ran toward the front of the train as a figure burst through the wall onto the roof, startling Tanjiro.

Riezel stopped the demon-fused Infinite Train by dismantling it with Decomposition Magic, saving the passengers and leaving Enmu exposed. Enmu, the last surviving Lower Rank Demon, struggled in the wreckage as Riezel approached.

• Tanjiro and Inosuke rushed along the train roof, trying to reach its vital point before it struck Riezel.
• Riezel touched the locomotive with Crimson Wave and punched the dismantled train apart, scattering its carriages and throwing Tanjiro and Inosuke into a field.
• Zenitsu emerged from a wrecked carriage in a panic, while Rengoku used Flame Breathing to stabilize the separated cars and bring them to a stop.
• Riezel identified the demon inside the locomotive as Enmu, Lower Rank One and the last surviving Lower Rank Demon.
• Enmu vowed to devour everyone and struggled inside the locomotive as Riezel walked toward him.

Riezel destroyed Enmu and saved everyone aboard the Infinite Train, but he warned Rengoku Kyojuro that an Upper Rank Demon was approaching. The newcomer arrived moments later and confirmed Enmu’s death, setting the stage for a confrontation.

• Enmu attacked Riezel with his Forced Sleep: Eyes Blood Demon Art, but Riezel resisted and cut apart the flesh pillars.
• Riezel unleashed Decomposition Magic at maximum output, erased Enmu and the locomotive, and ended the threat without harming the passengers or Demon Slayer Corps members.
• Rengoku Kyojuro invited Riezel to join the Demon Slayer Corps while they waited for help to handle the aftermath.
• Riezel announced that an Upper Rank Demon was coming, and Tanjiro, Zenitsu, Inosuke, and Rengoku Kyojuro sensed the approaching figure.
• The Upper Rank Demon crashed into the ground, emerged from the dust, and remarked that Enmu had died.

Upper Rank Three Akaza appeared after Enmu’s defeat and challenged Riezel and Rengoku Kyojuro. Rengoku fought Akaza alone at first, but after being knocked back, Riezel stepped forward to face the demon.

• Tanjiro, Zenitsu, Inosuke, and Rengoku sensed Akaza’s overwhelming fighting spirit as he emerged from the smoke and identified himself as Upper Rank Three.
• Akaza explained that he had come on orders to investigate Lower Rank One’s death, then focused on Riezel and Rengoku as the strongest opponents.
• Akaza launched a lightning-fast attack at Riezel, but Rengoku intercepted him with Flame Breathing and began fighting him.
• Rengoku and Akaza exchanged sword strikes and punches, while Akaza’s wounds healed almost instantly.
• Akaza knocked Rengoku backward, but Riezel appeared in front of him and took over the fight.

Akaza tried to persuade Riezel and Rengoku Kyojuro to become demons, arguing that human limits prevented them from reaching the supreme realm. Riezel rejected his claims and prepared to fight Akaza with Rengoku Kyojuro’s sword.

• Akaza sensed Riezel’s immense fighting spirit and invited him to become a demon, then urged Rengoku Kyojuro to join him as well.
• Rengoku Kyojuro refused, explaining that he would not give up sunlight or consume humans, and Tanjiro defended the value of human lives.
• Akaza attacked Tanjiro with a punch’s force, but Rengoku Kyojuro intercepted it with his blade.
• Riezel revealed that he had gained his current strength in four months and rejected Akaza’s belief that only demons could keep growing stronger.
• Akaza activated Destructive Death: Compass Needle, and Riezel borrowed Rengoku Kyojuro’s sword and began to breathe as the air around him grew scorching.

Riezel used Sun Breathing to defeat Upper Rank Three Akaza with one slash, then gave Akaza the name Tsugikuni Yoriichi. After the battle, Tanjiro recognized Riezel’s sword form as the same Dance connected to the Dance of the Fire God, while Demon Slayer Corps members arrived to handle the aftermath.

• Riezel’s breathing and fighting spirit changed, reminding Tanjiro of his father’s Kagura Dance and the Dance of the Fire God he had used against Rui.
• Akaza unleashed Destructive Death: Annihilation Style, and Riezel answered with Sun Breathing: First Form, Dance, cutting through the attack and Akaza’s neck.
• When Akaza asked Riezel’s name, Riezel replied, "Tsugikuni Yoriichi," and Akaza died from the slash.
• Tanjiro recognized Riezel’s sword technique as the familiar Dance, while Riezel returned Rengoku Kyojuro’s Nichirin Blade and remarked that it was heavy.
• Demon Slayer Corps Swordsmen and masked people arrived about ten minutes later to clear the battlefield and handle the aftermath.

After the Infinite Train incident, Rengoku Kyojuro took Riezel to meet the Demon Slayer Corps Master, while Tanjiro, Zenitsu, and Inosuke joined them on the way to Rengoku’s home. Meanwhile, a headless corpse vanished from the wreckage, and Muzan ordered Hantengu and Gyokko to investigate the human claiming to be Tsugikuni Yoriichi.

• The authorities classified the Infinite Train incident as an accidental derailment, and the Demon Slayer Corps remained uncredited for saving the passengers.
• Rengoku Kyojuro told Riezel that the Master wanted to meet him after hearing about him from a Kasugai Crow, and Riezel agreed in hopes of gaining help collecting Breathing Techniques.
• Tanjiro asked to accompany them so he could question Riezel and Rengoku, and Rengoku invited Tanjiro, Zenitsu, and Inosuke to his home.
• Riezel, Rengoku Kyojuro, Tanjiro, Zenitsu, and Inosuke departed while Demon Slayer Corps members stayed behind to clean up the wreckage.
• A headless corpse twitched and disappeared before the Demon Slayer Corps members could find it.
• Muzan reacted fearfully to the name Tsugikuni Yoriichi and summoned Hantengu and Gyokko to help him identify Riezel.

Rengoku Kyojuro brought Riezel to the Ubuyashiki Family residence, where all nine Hashira gathered to meet the swordsman reported to have slain an Upper Rank. Several Hashira doubted the report, and Sanemi Shinazugawa drew his sword to challenge Riezel as the chapter ended.

• Rengoku Kyojuro brought Riezel by covered carriage to the secluded Demon Slayer Corps Headquarters, while Tanjiro, Zenitsu, and Inosuke went to Rengoku's home.
• Rengoku Kyojuro announced their arrival, and all nine Hashira gathered around Riezel in the estate courtyard.
• Sanemi Shinazugawa, Obanai Iguro, Tengen Uzui, and Gyomei Himejima questioned whether Riezel had truly defeated an Upper Rank, while Mitsuri Kanroji and Shinobu Kocho spoke in his favor.
• Rengoku Kyojuro swore that his report was entirely true, but Sanemi Shinazugawa drew his sword and demanded that Riezel take one strike from him.

Riezel effortlessly defeated Sanemi Shinazugawa, Tengen Uzui, and Obanai Iguro after they challenged him in the courtyard. He revealed they lacked several advanced abilities, then addressed the hidden observer, who turned out to be the frail Master of the Demon Slayer Corps.

• Sanemi Shinazugawa attacked Riezel, who stopped his sword between two fingers and kicked him into a rockery.
• Tengen Uzui and Obanai Iguro attacked Riezel together, but he knocked them away with a flick of his sleeve and struck them with stones.
• Riezel told the Hashira that they could not defeat him without awakening their marks, Crimson Blades, and the Clear World.
• Riezel called out the person watching from the residence, and a voice admitted that he had hoped to see Sun Breathing.
• The Hashira knelt as their Master was helped into the courtyard, while Riezel noticed that the sickly man appeared to have little time left to live.

Riezel met Ubuyashiki Kagaya, who recognized his Sun Breathing as the lost origin of all Breathing styles and revealed its history to the Hashira. The Hashira learned that the Corps had erased Tsugikuni Yoriichi’s records after expelling him, leaving them shaken by the revelation.

• Ubuyashiki Kagaya welcomed Riezel to headquarters and thanked him for killing an Upper Rank Demon, the first to fall in over a century.
• Ubuyashiki Kagaya said Riezel’s Sun Breathing might allow the Corps to end its thousand-year conflict with demons.
• Ubuyashiki Kagaya explained that Tsugikuni Yoriichi had created the first Breathing style and that the other styles had branched from it.
• Ubuyashiki Kagaya revealed that Sun Breathing had been lost, and Sanemi Shinazugawa and Rengoku Kyojuro questioned why the Hashira had never heard of it.
• Riezel explained that Tsugikuni Yoriichi had been expelled after making a mistake and that others had maliciously erased the records of Sun Breathing.

Ubuyashiki Kagaya explained the Rengoku Family’s historical ties to Tsugikuni Yoriichi and invited Riezel to join the Demon Slayer Corps, but Riezel declined so he could pursue secluded training. Kagaya offered to help him obtain Breathing Techniques, and Riezel was sent to stay with Rengoku Kyojuro.

• Ubuyashiki Kagaya told the Hashira that the Rengoku Family had preserved records about Tsugikuni Yoriichi and Sun Breathing.
• Ubuyashiki Kagaya asked Riezel to remain in the Demon Slayer Corps, but Riezel declined because he wanted time to study secret techniques and train.
• Ubuyashiki Kagaya offered to help Riezel even if he did not join, and Riezel requested the five foundational Breathing Techniques.
• Ubuyashiki Kagaya assigned Rengoku Kyojuro to host Riezel and ended the gathering.

Riezel settled into the Rengoku Family home and received the five fundamental Breathing Technique books. He asked for Nichirin Blade ores and decided to forge an exclusive blade himself using magic.

• Riezel moved into the Rengoku Family home, where he watched Inosuke chase Zenitsu in a locomotive costume while Tanjiro trained with his wooden box on his back.
• Rengoku Kyojuro delivered the five compiled volumes of the fundamental Breathing Techniques and offered to answer Riezel's questions about Flame Breathing.
• Riezel asked Rengoku Kyojuro to obtain Scarlet Crimson Sand Iron and Scarlet Crimson Ore for a Nichirin Blade.
• Rengoku Kyojuro offered to have Swordsmith Village forge the blade, but Riezel declined and explained he planned to make it himself.
• Riezel planned to purify the ores with Decomposition Magic and fuse them with the Hermit's Sword using Construction System magic to create an exceptionally durable Nichirin Blade.

Riezel studied the five foundational Breathing Techniques, mastered them, and tested their forms in Rengoku’s courtyard. He then began planning to fuse Demon Slayer Breathing Techniques with the Akasha Continent’s sword skills, hoping to create a combat method that grew stronger with use.

• Rengoku Kyojuro agreed to bring Riezel as much Scarlet Crimson Sand Iron and Scarlet Crimson Ore as he could obtain.
• Riezel studied the five foundational Breathing Techniques and concluded that each excelled in different areas despite Sun Breathing’s overall strength.
• Riezel mastered Water, Flame, Wind, Stone, and Thunder Breathing and demonstrated their first forms, heavily damaging Rengoku’s courtyard.
• Riezel decided to combine Sun Breathing, the Demon Slayer world’s Breathing Techniques, and Akasha Continent sword skills into a new Special Grade Sword Skill.

Riezel attempted to fuse the Breathing Techniques of two worlds into a new Sun Breathing, enduring severe pain as he pushed his body through days of practice. Tanjiro and Rengoku Kyojuro chose to let him continue, and Riezel was still training when the chapter ended.

• Riezel reasoned that Sun Breathing could combine with the Akasha Continent's Breathing Techniques and sword skills to strengthen his entire body and potentially let him grow stronger continuously.
• Riezel began experimenting with different breathing methods, enduring painful symptoms as he tried to fuse their principles into Sun Breathing.
• Riezel trained in the courtyard for several days without eating, drinking, or sleeping, while Rengoku Kyojuro and the three protagonists avoided interrupting him.
• Tanjiro worried that Riezel's body would break down, but Rengoku Kyojuro urged him to trust Riezel and wait for his attempt to succeed.
• Tanjiro returned to his own training, while Riezel continued his attempts without resting.

After three months of brutal experiments that repeatedly left him near death, Riezel developed an extraordinary new way of breathing. As Rengoku Kyojuro and Shinobu Kocho watched, a terrifying heat suddenly erupted from Riezel, leaving them braced for danger.

• Riezel collapsed after seven days of training, and Rengoku Kyojuro took him to the Butterfly Mansion for treatment by Shinobu Kocho.
• Riezel recovered by the next day and returned to training; after he repeated the cycle of collapse and rapid recovery, Shinobu Kocho began to suspect his body was inhuman.
• Over the next three months, Riezel continued his experiments while the Hashira secretly observed him, and Tanjiro became Rengoku Kyojuro's Successor Disciple.
• Riezel's breathing changed into a powerful, unfamiliar rhythm that Shinobu Kocho and Rengoku Kyojuro could not explain.
• A roar sounded through the courtyard, and intense heat radiated from Riezel, scorching the ground and forcing Rengoku Kyojuro and Shinobu Kocho to retreat into defensive stances.

After three months of dangerous experimentation, Riezel successfully developed an evolved Sun Breathing that greatly enhanced his combat strength. He reached the limit of his Level 5 abilities, awakened the Pioneer of the Sun Wheel skill, and began perceiving the Clear World.

• Riezel's intense heat scorched the courtyard until Rengoku Kyojuro called out to him, and the heat subsided as Riezel opened his eyes.
• Riezel confirmed that his evolved Sun Breathing fused Total Concentration Breathing with Akasha Continent sword skills, giving him the strength to challenge opponents above his level without side effects.
• Riezel updated his God's Blessing and reached Stage SSS in all five abilities at Level 5.
• Riezel discovered his new Pioneer of the Sun Wheel skill, which made him a Spiritual Being, doubled his light and heat magic effects, granted resistances, and strengthened his attacks against evil targets.
• Riezel looked at Rengoku Kyojuro and Shinobu Kocho and saw through their bodies, recognizing that he might have entered the Clear World.

After completing his Sun Breathing evolution, Riezel discovered he had entered the Clear World and discussed his next training goals with Rengoku Kyojuro and Shinobu Kocho. He then inspected the Scarlet Crimson Sand Iron and Scarlet Crimson Ore Rengoku had gathered, preparing to use them.

• Riezel realized his training had led him to master the Clear World, allowing him to perceive the inner workings of others' bodies.
• Rengoku Kyojuro and Shinobu Kocho considered how Riezel's new strength might help the Demon Slayer Corps defeat the demons, and Riezel thanked them for supporting his training.
• Riezel refused Shinobu Kocho's request to study his body and said he would work on mastering Total Concentration: Constant.
• Rengoku Kyojuro told Riezel he had gathered the Scarlet Crimson Sand Iron and Scarlet Crimson Ore, and Shinobu Kocho left to report Riezel's success to Ubuyashiki Kagaya.
• Rengoku Kyojuro showed Riezel the ores in the Rengoku Family warehouse, and Riezel accepted them and began channeling magic power.

Riezel purified Scarlet Crimson Sand Iron and Scarlet Crimson Ore, then fused their essence with the Hermit's Sword to forge a personal Nichirin Blade. The new weapon, named the Hermit, was complete in his hands.

• Riezel used Decomposition Magic to remove impurities from the Scarlet Crimson Sand Iron and Scarlet Crimson Ore, concentrating their essence into a single raw ore.
• Riezel decided to reforge the Hermit's Sword because its performance no longer matched his strength and Sun Breathing style.
• Riezel carefully unraveled the Hermit's Sword's structure and fused it with the raw ore while preserving its Indestructible Attribute.
• Riezel shaped the molten metal into a Thousand-Blade Demon Sword-inspired blade with a black hilt, godlike patterns, and a fiery crimson glow.
• Riezel inscribed "Hermit" on the hilt and gripped his completed personal Nichirin Blade.