Chapter Summaries

Tetsu no Sosuke returned to his former home with Kanae and Kotetsu, where he found a large gift of Scarlet Sand Iron and considered reforging his hammer and Nichirin Blade. Kotetsu explained how his Mechanism Arts and magnetic control device had enabled him to rebuild the Automaton Puppet, though it was less powerful than the original training puppets.

• Tetsu no Sosuke opened Kawahara Chintetsu's gift crate and found a large supply of Scarlet Sand Iron.
• Kanae suggested that Tetsu no Sosuke use the iron to reforge his Nichirin Blade and have words engraved on it now that he was a Pillar.
• Tetsu no Sosuke avoided discussing his Pillar title and asked Kotetsu how he had made the Automaton Puppet obey him.
• Kotetsu explained that he had developed a magnetic control device using the Mechanism Arts Tetsu no Sosuke had taught him.
• Kotetsu rebuilt the Automaton Puppet around his control device, though it was weaker than Tetsu no Sosuke's training puppet and the one inherited by Kotetsu's family.

Kotetsu showed Tetsu no Sosuke and Kanae the remote-controlled Automaton Puppet and its mechanism board. Tetsu no Sosuke praised Kotetsu’s talent and began considering how the simple board worked.

• Kotetsu brought out his Automaton Puppet when Tetsu no Sosuke returned and laughed at his astonishment.
• Tetsu no Sosuke threatened to take the puppet apart, then playfully ground his fist against Kotetsu’s head until he begged for mercy.
• Kotetsu proudly showed Tetsu no Sosuke and Kanae the mechanism boards he had made through repeated attempts.
• Tetsu no Sosuke recognized the board’s simplicity and praised Kotetsu’s talent, moving Kotetsu deeply.
• Kotetsu ran outside, while Tetsu no Sosuke picked up the board and began imagining possible control systems.

Sosuke planned to strengthen the Demon Slayer Corps by designing systems for Kotetsu to build into the Automaton Puppet. He spent the day drawing instructions with Kanae, then took her to the Mountain Top Hot Spring before Kotetsu arrived the next morning.

• Sosuke explained to Kanae how the Corps could produce and distribute equipment based on his designs, and she welcomed the idea.
• Sosuke sketched and labeled the systems for Kotetsu while Kanae kept him company.
• Sosuke and Kanae ate food supplied by Kawahara Chintetsu, then went to the Mountain Top Hot Spring under cover of darkness.
• Kanae told Sosuke how he had surprised her at the spring on his earlier visit.
• Kotetsu came knocking early the next morning.

Tetsu no Sosuke gave Kotetsu plans for a Combat Automaton and began reforging new Nichirin Blades for himself and Kanae. While forging, he discovered he could perceive flaws in iron and realized the material needed the right balance of purity.

• Tetsu no Sosuke handed Kotetsu his drawings and told him to work with the Village Chief to develop a Combat Automaton.
• Kotetsu eagerly ran off to find the Village Chief with the drawings.
• Tetsu no Sosuke told Kanae he would reforge both of their Nichirin Blades using the scarlet sand iron.
• Tetsu no Sosuke forged the two blades together and discovered he could see flaws in the iron.
• Tetsu no Sosuke realized that iron did not need to be as pure as possible, but needed to be just right.

Tetsu no Sosuke used the Breath of the Sun while forging two Nichirin Blades, and his careful work pushed their Sharpness Level to 6. After Kanae teased him about his plain, hammer-shaped guard, the successful forging notifications rewarded him with guides.

• Tetsu no Sosuke controlled his hammer strikes to strengthen the iron as he removed its impurities.
• Kanae watched him work, cooked for him, and shared meals with him over the following days.
• After three days, Tetsu no Sosuke finished two Nichirin Blades, one with Kanae's familiar guard and one with a plain square guard.
• Kanae said Tetsu no Sosuke's guard looked like the face of a hammer, leaving him silent and dismayed.
• The forging notifications showed both blades had reached Sharpness Level 6 and awarded Tetsu no Sosuke a Swordsmanship Guide and a Meditation Guide.

Tetsu no Sosuke received Swordsmanship and Meditation Guides while Kanae tried her new Nichirin Blade and felt stronger. After they ate lunch, he prepared to make a scabbard and asked Kanae whether she had thought of a name for her blade.

• Tetsu no Sosuke examined his Swordsmanship and Meditation Guides and reflected that they had arrived late.
• Kanae tested her new Nichirin Blade with a series of graceful forms and said it made her feel stronger.
• Tetsu no Sosuke warned Kanae not to rely entirely on her weapon, and they made lunch together.
• After lunch, Tetsu no Sosuke planned to make a scabbard before they left Swordsmith Village.
• Tetsu no Sosuke asked Kanae whether she had thought of a name for her blade.

Kanae named her Nichirin Blade Flower Language, and Tetsu no Sosuke explained why naming a blade might strengthen its effects. After struggling to choose a name for his own sword, he settled on Fire, though Kanae suggested Sunblaze instead.

• Kanae named her Nichirin Blade Flower Language, and Tetsu no Sosuke proposed calling his sword Flower Mist.
• Tetsu no Sosuke explained that Kyojuro Rengoku’s named and well-maintained blade seemed to keep its effects active even when he was only carrying it.
• Kanae teased Tetsu no Sosuke with names including Little Hammer and Fire Hammer because he was the Hammer Pillar.
• Tetsu no Sosuke decided to name his blade Fire, and Kanae suggested Sunblaze as a better name.

Tetsu no Sosuke finished the Sunflare Hammer’s Scarlet Sand Iron scabbard and prepared to leave Swordsmith Village with Kanae. On their return journey, he noticed Kanae was cold and gave her his Haori.

• Tetsu no Sosuke decided to name his blade the Sunflare Blade and its scabbard the Sunflare Hammer.
• Tetsu no Sosuke forged the Scarlet Sand Iron scabbard but received no reward for making it.
• Kotetsu and the Village Chief continued arranging for skilled Swordsmiths to study Tetsu no Sosuke’s blueprints.
• Tetsu no Sosuke and Kanae visited Kawahara Chintetsu before leaving Swordsmith Village, and he told Tetsu no Sosuke to take care of himself.
• Tetsu no Sosuke noticed Kanae shivering on their return journey and draped his Haori over her shoulders.

Kanae felt unusually cold, hungry, and emotional while traveling with Tetsu no Sosuke. When he returned from hunting, he found her crying and immediately feared someone had hurt her.

• Kanae told Tetsu no Sosuke she felt cold and hungry again shortly after they had eaten.
• Tetsu no Sosuke teased Kanae about her appetite, then promised to find her something to eat.
• He left Kanae waiting by a rock, gave her his coat, and told her to stay nearby.
• After he left, Kanae suddenly felt hurt and began to cry, though she could not explain why.
• Tetsu no Sosuke returned about half an hour later with a rabbit and found Kanae sobbing.
• Tetsu no Sosuke searched for whoever might have upset Kanae and felt murderous toward them.

Kanae cried because she felt hungry and missed Tetsu no Sosuke, leaving him puzzled by her sudden emotional changes. After he worried that he had upset her, Kanae reassured him that she was happy and showered him with kisses.

• Kanae threw herself into Tetsu no Sosuke's arms, cried against his chest, and said she was hungry.
• Tetsu no Sosuke noticed Kanae had been getting hungry faster and wondered if he had caused her tears.
• Kanae said she did not know why she had cried and asked him to let it go.
• Tetsu no Sosuke roasted a rabbit and said he wanted to find out what had made her cry so he could keep her happy.
• Kanae kissed Tetsu no Sosuke and told him she was happy, but he still asked why she had been crying.

Tetsu no Sosuke and Kanae ate a roasted rabbit, but her sudden hunger and quick fullness worried him. He decided to ask Shinobu Kocho to examine Kanae when they returned, then packed the leftovers and continued their journey with her.

• Tetsu no Sosuke stopped Kanae from eating the rabbit before it was fully cooked.
• Kanae eagerly ate one rabbit leg, then said she was full after only two bites of the second.
• Tetsu no Sosuke wondered whether Kanae's appetite and mood swings signaled a problem and decided Shinobu Kocho should examine her.
• Tetsu no Sosuke packed the remaining rabbit meat and took Kanae's hand as they continued their journey.

Tetsu no Sosuke brought Kanae back to the Butterfly Estate after worrying over her unusual sleepiness, appetite, and mood changes. He asked Shinobu Kocho to discreetly check Kanae’s health, leaving the cause of her symptoms unresolved.

• Tetsu no Sosuke and Kanae stayed overnight in a village, where he secretly left money for the kind villagers.
• Tetsu no Sosuke noticed that Kanae was unusually sleepy during their journey and hurried to return to the Butterfly Estate.
• Kanae told Shinobu Kocho that Tetsu no Sosuke had rushed her back and went inside to catch up on sleep.
• Tetsu no Sosuke asked Shinobu Kocho to examine Kanae without letting her notice, then described her symptoms.
• Shinobu Kocho could not identify what was causing Kanae’s symptoms, and Tetsu no Sosuke asked her not to worry Kanae.

After the Hidden brought Tetsu no Sosuke’s Artisan Set, Shinobu Kocho examined her sister and found nothing obviously wrong. Tetsu no Sosuke later received Tanjiro’s letter about the Automaton Puppet and decided to let Iron Head handle its changes himself.

• The Hidden arrived with Tetsu no Sosuke’s Artisan Set, so he helped put everything back in place.
• Shinobu Kocho examined her sister and told Tetsu no Sosuke that she had no fever or other apparent problem.
• Tetsu no Sosuke received Tanjiro’s letter describing changes to the Automaton Puppet.
• Tetsu no Sosuke wrote back to Iron Head, telling him not to worry and to focus on training.

As Tetsu no Sosuke prepared to leave, he worried about Kanae’s recurring fatigue and her repeated refusals of intimacy. The night before his departure, Kanae finally began to tell him about something she had been afraid to share.

• Tetsu no Sosuke noticed Kanae’s fatigue repeatedly return, though Shinobu Kocho found nothing wrong with her.
• Kanae continued eating and training, but shortened her sessions and repeatedly turned down Tetsu no Sosuke’s advances.
• Tetsu no Sosuke treasured his remaining time with Kanae and felt hurt, but remained devoted to her.
• The night before leaving, Tetsu no Sosuke asked Kanae if she had anything to tell him.
• Kanae admitted she had been thinking about something but had not dared tell him without being sure.

Kanae told Tetsu no Sosuke that her symptoms and missed period might mean she was pregnant, leaving them waiting for confirmation. Tetsu no Sosuke was overwhelmed with joy and surprise.

• Kanae explained that she had been sleepy, hungry, sluggish, slightly feverish, and nauseous, and that her period had not arrived.
• Kanae told Tetsu no Sosuke that books listed her symptoms as possible early signs of pregnancy.
• Tetsu no Sosuke was stunned and gently placed a hand on Kanae’s lower abdomen, unable to contain his emotions.
• Kanae reminded Tetsu no Sosuke that they could not yet be sure and would need to wait longer to confirm it.

Tetsu no Sosuke and Kanae discussed the possibility that Kanae was pregnant, with Kanae worrying that the books might be wrong. The chapter ended with Tetsu no Sosuke warning her not to take medicine carelessly in case it could harm the baby.

• Tetsu no Sosuke credited their diligence for Kanae's possible pregnancy, embarrassing her.
• Kanae admitted she was worried that the pregnancy might not be real because she had no visible signs yet.
• Tetsu no Sosuke advised Kanae to be careful during the early stages and claimed he had heard the risks from the Hidden.
• Kanae agreed the Hidden gossiped too freely and said she would raise the issue with the Master.
• Kanae described her mood swings, sleepiness, and hunger, and Tetsu no Sosuke warned her not to take medicine without care.

Kanae told Tetsu no Sosuke that she might be pregnant, just as he was preparing to leave for his new post. She considered stepping down as a Pillar if the pregnancy was confirmed, and his realization that she might have chosen this left him wondering what she wanted.

• Kanae told Tetsu no Sosuke she suspected she was pregnant and had avoided certain foods and strenuous training.
• Tetsu no Sosuke urged Kanae to share her worries with him and offered to delay his departure, but she insisted he fulfill his duties.
• Kanae reminded Tetsu no Sosuke that a pregnant woman could not serve as a Pillar and said she might step down to stay with him.
• Tetsu no Sosuke asked whether Kanae would regret leaving the Corps, and she replied that she was a doctor.
• Tetsu no Sosuke realized Kanae could have avoided becoming pregnant if she had wanted to, and wondered whether she had chosen it herself.

Kanae told Tetsu no Sosuke how much she wanted to spend her life with him and shared her joy that she might be pregnant. Tetsu no Sosuke stayed with her as she fell asleep, then woke early the next morning still thinking about becoming a father.

• Kanae asked Tetsu no Sosuke if her wish to stay with him was selfish, and he reassured her it was natural.
• Kanae explained that she had hoped to become pregnant but had expected it to take longer, and called the pregnancy a reward for their hard work.
• Tetsu no Sosuke promised not to let Kanae down, and she told him she trusted him completely.
• Kanae said she might know for sure in ten to twenty days, then fell asleep in Tetsu no Sosuke's arms.
• Tetsu no Sosuke watched over Kanae through the night and woke early the next morning thinking about becoming a father.

Tetsu no Sosuke woke delighted that Kanae was pregnant, then became anxious about leaving her behind and began arranging her care. He headed off to notify the Master, but Shinobu Kocho stopped him and demanded an explanation.

• Tetsu no Sosuke touched Kanae's abdomen, then kissed her cheek and got up while she continued sleeping.
• Tetsu no Sosuke told Kiyo Terauchi to prepare suitable food and gave her detailed instructions about Kanae's meals and drinking water.
• Tetsu no Sosuke told Shinobu Kocho to protect Kanae from heavy work, climbing, injuries, training, and missions, and to contact him if a mission arose.
• Shinobu Kocho questioned Tetsu no Sosuke's strange instructions, but he hurried away to write to the Master.
• Shinobu Kocho grabbed Tetsu no Sosuke and insisted that he explain himself before leaving.

Tetsu no Sosuke told Shinobu Kocho that her sister was probably pregnant and that he would leave as planned. He left Shinobu in charge of the Butterfly Estate, and she was left fuming after he told her to make her bed.

• Shinobu Kocho pressed Tetsu no Sosuke to explain why he seemed strange.
• Tetsu no Sosuke told Shinobu Kocho that her sister was probably pregnant and had kept the news secret until the night before.
• Shinobu Kocho realized her sister's earlier symptoms might have indicated pregnancy and asked what would happen to the Butterfly Estate.
• Tetsu no Sosuke told Shinobu Kocho that the Butterfly Estate was up to her and said she was already qualified to take charge.
• Shinobu Kocho tried to follow Tetsu no Sosuke to see her sister, but he told her to make her bed and hurried away.