Chapter Summaries

Su Chen fought through Autumn Sky Mountain, escaped a Blood Demon Art that distorted his sense of direction, and found the cabin where Shinobu Kocho was trapped. He killed the demon controlling the mist and discovered Lower Rank Two, Rokuro, inside, preparing to test his strength against him.

• Su Chen killed demons as he climbed Autumn Sky Mountain, then used Bullet Time to spot and pass through the blood mist confusing his direction.
• Su Chen followed the sounds of demons to the summit and overheard a demon explain that his Blood Demon Art had trapped Shinobu Kocho and other women.
• Su Chen decapitated the demon leaving the cabin, apparently ending its Blood Demon Art.
• Su Chen saw a dozen demons inside the cabin and recognized the large demon among them as Lower Rank Two, Rokuro.
• Su Chen decided to fight Rokuro and test the strength he had gained through training.

Su Chen stormed the demons’ gathering and killed its members before defeating Lower Rank Six Rokuro with a wisteria-coated blade. Rokuro summoned Lower Rank Four Koyuki, and Lower Rank Three Byōyō appeared as Su Chen faced the two demons.

• Su Chen kicked in the door and quickly beheaded the drunken demon Lao Duan.
• Su Chen used Bee Breathing and wisteria to kill the other demons in the room.
• Rokuro attacked Su Chen, but Su Chen severed Rokuro’s hands and legs, preventing him from regenerating.
• Rokuro called for Koyuki, but Su Chen cut off his head as she appeared.
• Lower Rank Three Byōyō appeared and comforted Rokuro’s severed head while Su Chen assessed the two demons.

Su Chen used Bullet Time to defeat Lower Ranks Byōyō and Koyuki, but the effort left him exhausted. As he tried to recover, someone stabbed him in the back.

• Rokuro dissolved after Byōyō and Koyuki refused to save him, and he warned them that Su Chen would kill them too.
• Su Chen activated Bullet Time as Byōyō and Koyuki attacked him from opposite sides, then created Ghost Shadow Footwork and Bee Breathing, Eighth Form-Blood Demon Bee Fang.
• Su Chen cut 156 pieces of bone from Byōyō and Koyuki, leaving them unable to move freely as their bodies regenerated.
• Su Chen told the demons he was keeping them alive because they were useful, silenced Koyuki by cutting off Fallen Leaves' head, and sat down to recover.
• As Su Chen rested after overusing Bullet Time, an unseen attacker plunged a sharp weapon into his back.

Su Chen discovered that the old man he had met was a human who had helped demons in hopes of becoming one, and he killed Koyuki and Byōyō after they fed on the dead. As Shinobu Kocho’s party advanced toward the summit, she wondered whether Doma was behind the demons’ coordinated attacks, and the path ahead suddenly changed.

• Su Chen realized the old man had attacked him because he wanted the demons to turn him into one, and understood that humans had helped cause Shinobu Kocho’s injury.
• Koyuki killed and ate the old man, so Su Chen cut off her limbs and killed her after she revealed that Doma had wanted Shinobu Kocho captured and eaten.
• Byōyō began feeding on Koyuki’s corpse, and Su Chen destroyed his head as well.
• Shinobu Kocho led the injured Demon Slayer Corps members toward the summit, suspecting the demon with the fans—Doma—of coordinating the demons.
• A Corps member noticed that the path ahead had changed.

Shinobu Kocho found evidence that Su Chen had killed demons, including a member of the Twelve Kizuki, and realized he had been injured. In the Infinity Castle, Muzan killed Kamanué, strengthened Enmu, and sent him to hunt Su Chen.

• Shinobu Kocho examined the bloodstained house and found signs that someone had killed numerous demons, including a Twelve Kizuki member, with wisteria poison.
• Shinobu Kocho recognized the poison as linked to Su Chen and identified a pool of blood as likely his, then hurried away to find him.
• Muzan searched the Lower Ranks' memories and learned that Lower Ranks Two, Three, Four, and Five had been killed.
• Muzan snapped Kamanué's neck after Kamanué's thoughts irritated him, then rewarded Enmu for his flattering speech with more blood.
• Muzan showed Enmu images of Su Chen and ordered him to kill the young man, then sent the enhanced Enmu out of the Infinity Castle.

After returning to the Butterfly Mansion at dawn, Shinobu Kocho let Su Chen treat her injured arm and revealed her anger and grief over her sister Kanae Kocho’s death. Su Chen later collapsed from exhaustion, and when he woke in the afternoon, Kanao Tsuyuri and the other girls gathered around him.

• Su Chen waited at the Butterfly Mansion and noticed Shinobu Kocho’s injured arm when she returned.
• Su Chen treated Shinobu Kocho’s wound, and she admitted that she had long been angry about demons killing Kanae Kocho and that she felt unable to fulfill her sister’s dream.
• Shinobu Kocho left after thanking Su Chen, while a girl watched him leave from a second-floor window.
• Su Chen collapsed from exhaustion after going inside and woke in the afternoon with Kanao Tsuyuri beside him.
• Aoi Kanzaki noticed Su Chen was awake and called Kiyo, Sumi, and Xiao Caihui to come see him.

After waking from overusing Bullet Time, Su Chen learned that Shinobu Kocho had cared for him and spent time alone with Kanao Tsuyuri. He then went with Kanao to meet Kyojuro Rengoku and Senjuro Rengoku at the Flame Hashira's training ground, where Kyojuro announced a test for him.

• Su Chen woke up to find his back treated and bandaged, and heard that Shinobu Kocho had watched over him before going to see the Master.
• Kanao Tsuyuri stopped Aoi Kanzaki and the little girls from crowding Su Chen, then stayed with him after they left.
• Su Chen apologized for breaking Kanao Tsuyuri's Nichirin Blade and considered forging her a replacement.
• Su Chen arrived with Kanao Tsuyuri at the Flame Hashira's training ground, where Kyojuro Rengoku and Senjuro Rengoku had been waiting under the sun.
• Kyojuro Rengoku greeted Su Chen and said they would test him instead of training that day.

Su Chen visited Kyojuro Rengoku’s training grounds for a test arranged by the Master, where Senjuro demanded that Kyojuro teach him a lesson. After agreeing to a match, Su Chen reviewed his abilities and planned to learn Flame Breathing while keeping Bee Breathing secret.

• Su Chen arrived at the training grounds with Kanao Tsuyuri, and Kyojuro explained that the Master had arranged training tailored to Su Chen’s weaknesses.
• Senjuro complained that Su Chen was late and demanded that Kyojuro teach him a lesson, and Su Chen agreed to face Kyojuro after the assessment.
• Kanao Tsuyuri worried about the match, and Su Chen reassured her before taking her hand.
• Kyojuro misunderstood Senjuro’s demand, then laughed when Su Chen explained it, and the group agreed to hold their match after the assessment.
• While Kyojuro and Senjuro fetched swords, Su Chen reviewed his three Breathing Styles and decided to keep Bee Breathing hidden and learn Flame Breathing.

Su Chen sparred with Kyojuro Rengoku to learn Flame Breathing and used Bullet Time, Butterfly Footwork, and his Demon Slayer Mark to evade the Hashira’s powerful attacks. Kyojuro stopped when Su Chen neared his limit, leaving their sparring unfinished.

• Su Chen and Kanao received Nichirin Blades, and Su Chen tested the Flame Breathing sword that had belonged to Kyojuro’s father.
• Kyojuro recognized Su Chen’s strength and agreed to spar with him without a preliminary test.
• Kyojuro attacked with Flame Breathing, First Form: Unknowing Fire, and Su Chen dodged using Butterfly Footwork.
• Su Chen activated Bullet Time, read Kyojuro’s movements, and evaded Flame Breathing, Fifth Form: Flame Tiger.
• Su Chen’s Demon Slayer Mark appeared, and he switched to Ghost Shadow Footwork to avoid Kyojuro’s attacks.
• Kyojuro noticed Su Chen was nearing his limit, sheathed his blade, and ended the spar.

After sparring with Kyojuro Rengoku, Su Chen entered a state of enlightenment and independently mastered Total Concentration: Constant and the advanced Total Concentration: Focus. He then learned nearly all of Flame Breathing, and Kyojuro invited him to become his Tsuguko.

• Su Chen survived Kyojuro Rengoku's Unknowing Fire and Flame Tiger, impressing Senjuro Rengoku and Kanao Tsuyuri.
• Su Chen sat in meditation for two hours and discovered Total Concentration: Constant and Total Concentration: Focus by analyzing Kyojuro's breathing.
• Kyojuro praised Su Chen's rapid progress, and Su Chen resumed sparring with him.
• Su Chen learned Kyojuro's Flame Breathing forms, including Unknowing Fire, Rising Scorching Sun, Blooming Flame Undulation, and Flame Tiger.
• Kyojuro invited Su Chen to become his Tsuguko and offered to teach him Flame Breathing.

Su Chen learned from Kyojuro that demons were searching for a Black-clothed Masked Man, who was secretly Su Chen himself. After discovering Kyojuro’s neglected leg injury, Su Chen treated it, leaving Kyojuro amazed when he declared the treatment finished.

• Kyojuro told Su Chen that demons had begun acting with purpose and were searching for a Black-clothed Masked Man the Demon Slayer Corps also wanted to find.
• Su Chen realized that he was the masked man and worried that Muzan had already targeted him, so he considered using more aliases.
• Kyojuro tried to stand but collapsed because of a long-neglected calf injury, and Senjuro explained that missed appointments had left it untreated.
• Su Chen examined Kyojuro’s leg and began treatment with Kanao Tsuyuri assisting him.
• Su Chen finished treating Kyojuro, who widened his eyes in surprise and moved his leg.

Su Chen healed Kyojuro's leg and identified his forceful footwork as the likely cause of the injury. After demonstrating that he had memorized the earlier Flame Breathing forms and altered their footwork, Su Chen asked Kyojuro to perform Ninth Form: Rengoku so he could find the problem.

• Su Chen treated Kyojuro's leg, and Kyojuro and Senjuro thanked him as he said Kyojuro would need another treatment at the Butterfly Mansion.
• Su Chen explained that Kyojuro's leg pain came from applying force incorrectly, and Kyojuro admitted that explosive techniques made his legs hurt.
• Su Chen concluded that Kyojuro had caused the injury himself and asked him to demonstrate Flame Breathing, Ninth Form: Rengoku.
• Su Chen drew his Nichirin Blade and performed First Form: Unknowing Fire, showing the Rengoku brothers that he had memorized the earlier forms and used different footwork.
• Kyojuro hesitated when Su Chen asked him to perform Ninth Form so he could identify the cause of the leg injury.

Kyojuro decided to teach Su Chen Flame Breathing despite Senjuro’s objections, and demonstrated its Ninth Form. Su Chen’s comprehension awakened Bullet Domain, allowing him to analyze Flame Breathing’s flaws and create a preliminary upgraded style called Blazing Breathing.

• Senjuro protested that Flame Breathing belonged to the Rengoku Family and pleaded with Kyojuro not to teach it to Su Chen.
• Kyojuro explained that he acknowledged Su Chen and swore to commit seppuku if Su Chen betrayed the Demon Slayer Corps or became a demon.
• Senjuro accepted Kyojuro’s decision and resolved to train hard enough to master Flame Breathing before Su Chen.
• Kyojuro demonstrated Flame Breathing, Ninth Form: Rengoku, while Su Chen used Bullet Time to observe him.
• Su Chen’s comprehension upgraded Bullet Time into Bullet Domain, and he simulated Flame Breathing to identify flaws and develop improvements.
• Su Chen created a preliminary upgraded Breathing Style called Blazing Breathing, then recovered to see Kyojuro’s slash cleave through the nearby mountain forest.

Su Chen learned Kyojuro Rengoku’s Flame Breathing after watching it once, then used it to create the stronger Blazing Breathing and awaken a Bright Red Nichirin Sword. Kyojuro realized the new style could greatly strengthen the Rengoku Family, while Kanao watched Su Chen with admiration.

• Senjuro praised Kyojuro’s demonstration, while Kanao felt discouraged until Su Chen reassured her that he would teach her.
• Su Chen borrowed Kyojuro’s Nichirin Blade and performed Flame Breathing’s First Form, Unknowing Fire, with flawless technique.
• Su Chen used Total Concentration and demonstrated Blazing Breathing’s First Form, creating real flames that stunned everyone present.
• Su Chen’s rapid sword swings heated the blade until it turned reddish black and became a Bright Red Nichirin Sword.
• Kyojuro recognized Blazing Breathing as faster, hotter, and more powerful than Flame Breathing, and saw its potential for the Rengoku Family.
• Kanao watched Su Chen with quiet admiration, while Su Chen remained dissatisfied with his performance.

Su Chen taught Kyojuro and Senjuro the Blazing Breathing techniques, then refined Kyojuro’s Nichirin Blade while demonstrating them. He left with Kanao Tsuyuri before the Rengoku brothers could ask about the Bright Red Nichirin Sword, and they planned to visit him at the Butterfly Mansion.

• Su Chen agreed to teach Kyojuro Blazing Breathing, explaining that he had derived it from Flame Breathing.
• Kyojuro and Senjuro listened to Su Chen’s instruction for about two hours, with Kyojuro grasping some of the basics while Senjuro understood none.
• Su Chen returned Kyojuro’s blade after using his flames to refine it, saying it might become a Bright Red Nichirin Sword.
• Su Chen took Kanao Tsuyuri’s hand and hurried away before the Rengoku brothers could question him further.
• Senjuro stopped Kyojuro from chasing Su Chen and reminded him that Su Chen needed rest before his competition with Shinazugawa.
• Kyojuro and Senjuro agreed to visit Su Chen at the Butterfly Mansion, and Senjuro asked his brother what he thought of Su Chen.

Su Chen celebrated what he had learned from Kyojuro and stopped in a grove to teach Kanao Total Concentration: Focus. Kanao grasped the technique quickly but breathed too impatiently, and Su Chen intervened when she began to hurt her lungs.

• Kyojuro praised Su Chen to Senjuro and regretted not taking him as his successor earlier.
• Su Chen reflected on learning Total Concentration: Focus and Flame Breathing, then creating Blazing Breathing after his fight with Kyojuro.
• Kanao stopped Su Chen in a grove and asked to learn, while Su Chen initially misunderstood her request.
• Su Chen realized Kanao wanted to learn a Breathing Style, noticed she had kept a Nichirin Blade, and forgave her for forgetting to return it.
• Su Chen demonstrated Total Concentration: Focus and promised to create a Breathing Style suited to Kanao.
• Kanao grasped Focus on her first attempt but inhaled too soon again, so Su Chen intervened when her lungs began to hurt.

Su Chen comforted Kanao Tsuyuri after helping her breathing, then teased her and encouraged her to trust her feelings. He proposed using her coin to decide whether she would follow her heart, but distracted her with a clap before the result was revealed.

• Su Chen massaged Kanao Tsuyuri's back until her breathing steadied, and she told him they now shared the same breathing.
• Su Chen teased Kanao Tsuyuri about liking him, and she blushed and avoided answering.
• Su Chen killed the mosquitoes around Kanao Tsuyuri and placed a flower on her swollen bite, reminding her she could change when she found something she liked.
• Su Chen asked Kanao Tsuyuri for her coin and proposed that she follow her heart if it landed face up.
• Su Chen tossed the coin, then clapped to draw Kanao Tsuyuri's gaze away before its result was shown.

Kanao Tsuyuri realized she could speak and make decisions for herself after Su Chen helped her understand what the coin toss had revealed. The next morning, Su Chen learned Shinobu had been summoned again and sneaked into her laboratory to read her diary.

• Kanao anxiously urged Su Chen to reveal the coin, then realized she had spoken fluently before he showed her his empty hand.
• Su Chen explained that Kanao had been hiding herself and had already made her own decision; Kanao thanked him and embraced him.
• Su Chen searched for the lost coin, but Kanao told him she no longer needed it because she had found something more important and wanted to go home with him.
• Kanao fell asleep, so Su Chen carried her home; he later spotted the coin shining on top of the flowers.
• The next morning, Su Chen learned from Kiyo that Kagaya Ubuyashiki had summoned Shinobu again.
• After the girls left, Su Chen sneaked into Shinobu Kocho's laboratory and picked up her diary.

Su Chen secretly read the rest of Shinobu Kocho’s diary and learned that she had fallen for him, hidden his identity from the Master, and missed her sister. He realized Shinobu had poisoned herself to prepare for fighting Doma and resolved to protect her, just as someone approached the basement.

• Su Chen pretended to close Shinobu Kocho’s diary but read her entries about Autumn Sky Mountain, where she discovered he had saved her and secretly kept his identity from the Master.
• Shinobu’s diary revealed that she had nearly fallen for Su Chen, cared for him after he collapsed, and asked Rengoku to train him so he would not be hurt again.
• Su Chen realized Shinobu had been injecting herself with wisteria poison to prepare to kill Doma, leaving her body saturated with enough poison to kill almost any demon.
• Su Chen resolved to protect Shinobu and capture Doma for research, then heard footsteps approaching the basement.

Su Chen learned that the Butterfly Mansion was overwhelmed by wounded Demon Slayer Corps members and short on funds, while Aoi Kanzaki explained Shinobu's loneliness and the staff's financial difficulties. After reassuring Aoi that her work mattered, Su Chen spoke with Kanao Tsuyuri, who asked if he would stay at the mansion after his match with Shinazugawa, and he offered her a coin.

• Aoi Kanzaki told Su Chen that Shinobu had changed after Kanae's death and described how the mansion staff struggled to support her.
• Su Chen reassured Aoi that caring for patients was as important as fighting demons, and she thanked him before returning to help the staff.
• Aoi explained that the mansion was crowded with injured slayers and nearly out of money because its funding depended on the Hashira stationed there, while Shinobu refused to ask Oyakata-sama for help.
• Su Chen went to practice swordsmanship and met Kanao Tsuyuri, who asked whether he would stay at the Butterfly Mansion after his match with Shinazugawa.
• Su Chen told Kanao he would stay if she welcomed him, and then took a coin from his pocket and offered it to her.