Chapter Text
When the group arrived at the Butterfly Mansion, they were immediately greeted by Kanao, Aoi, Senjurou, and the Caterpillars. “Alright!” Aoi declared as the Kakushi wheeled the injured Slayers in. “Any life-threatening injuries or anything to take priority?” she asked. Everyone turned to Tanjirou’s box as it began to open, and the demon within emerged.
“Oh!” someone exclaimed as Tanjirou leapt out of the cart carrying his box and sister.
“Is that Tanjirou?” Kiyo gasped.
“Yeah, I think so!” Naho replied.
“But how is he in the sun? Isn’t he still a demon?” Sumi inquired while Tanjirou turned to the group of Butterfly Girls. His gaze lit up, and he began running to the group at the gate.
“Tanjirou, wait!” a Kakushi called out as they all scrambled to catch him. Tanjirou kept out of reach, however, and skidded to a stop in front of Kanao.
“Good morning, Kanao!” he greeted the older girl cheerfully. Kanao’s eyes widened, and all the Butterfly Mansion residents could see the red crawling up the Slayer’s face.
“He-hello… Tanjirou.” Kanao replied softly while Aoi turned to Nezuko. Out cold. Aoi turned back to Kanao and Tanjirou. The former was steadily getting redder while the latter babbled with whatever words he’d managed to pick up since… whenever he began talking again. If this kept up, Aoi was worried Kanao might end up passing out.
“Tanjirou?” Senjurou spoke up, getting the demon’s attention. With how bright Tanjirou’s smile got, Aoi wondered if one could go blind from such a thing. Tanjirou hugged Senjurou tightly, lifting the boy up. “It’s good to see you, too.” Senjurou chuckled. “Let’s get everyone settled, okay?” he asked.
“Okay!” Tanjirou replied cheerfully, returning to Nezuko’s cart and repeating ‘good morning’ as he went. Aoi shook her head with a fond, if slightly exasperated, smile. She turned to Kanao, finding her to be standing completely still. The poor girl’s face was so red that she looked like a tomato, maybe even a beet.
“Is Miss Kanao okay?” Sumi asked.
“I think so.” Aoi replied. “Just a little flustered, is all.” Senjurou gently tapped Kanao’s shoulder, and the older girl jumped slightly as the carts were wheeled into the Butterfly Mansion. Tanjirou waved enthusiastically as he passed, and everyone else returned the wave.
When Nezuko woke up, there were three demons surrounding her bed. “Hey.” she mumbled groggily as she sat up, her gaze drifting to her right foot. It was bandaged. “How long was I out?” she asked.
“Only a week, thankfully.” Tamayo answered with a smile. “Though, the news we heard upon your arrival was quite a shock.”
“News?” Nezuko asked, trying to remember what could be so shocking. Tanjirou flopped onto her legs with a bright smile, not concealed by his muzzle.
“Nezuko!” he declared. “Is… is Nezuko okay? Nezuko feels… better?” As her brother spoke, Nezuko remembered what happened in the Swordsmith’s Village. Tanjirou burning in the sun, being so sure he was about to die, killing Upper Four in the most painful way she could in retaliation for Tanjirou’s life… Then Tanjirou, standing unscathed in the sunlight. She had nearly forgotten what her big brother looked like in the daylight.
“Yeah.” Nezuko whispered, wiping up her tears. “Yeah, I’m okay.” I’m so glad it wasn’t a dream. Tanjirou sat up with a worried pout, reaching up and wiping Nezuko’s cheeks.
“Don’t cry… Nezuko. Tanjirou is… okay. Nezuko is okay. Don’t… cry.” he said.
“They’re happy tears.” Nezuko chuckled, turning back to Tamayo and Yushiro.
“It’s truly remarkable.” Tamayo told her with a warm smile. “Now that Tanjirou’s conquered the sun, his mental development has been steadily improving. It will take time for him to regain his original vocabulary, as well as his full sense of self, but it’s certainly quicker than before.”
“We believe your brother may have been inhibiting his mental development to prepare for conquering the sun, and that’s why he remained in a toddler-like mindset all this time.” Yushiro added. “It will still be a process before he’s back in his human mind, but at least he’s begun to make progress since then.”
“But this will also present danger to you both.” Tamayo spoke up.
“Nothing unusual, we’ve had a target on our backs since Asakusa.” Nezuko sighed, combing her fingers through Tanjirou’s hair.
“It’s about to become much bigger.” Tamayo replied. “Now that Tanjirou has conquered the sun, Muzan will be after him more than ever.” Nezuko unconsciously tensed at that. Kibutsuji had already been trying to capture her brother, and now he was going to increase his efforts?
“Why is he so desperate to get a hold of Tanjirou?” she asked. Tamayo gave her a grim look.
“Because Kibutsuji’s primary objective is to conquer the sun, and become truly immortal.” she answered. “And he believes there are two ways by which he can achieve this. Either a rare flower called the Blue Spider Lily… or a demon that can walk under sunlight. And now, one of those ways is out there, and he will likely stop at nothing to locate Tanjirou.”
“And if he does?” Nezuko was scared to ask, but she had to know.
“If Muzan locates and captures Tanjirou… he will devour Tanjirou to absorb the properties of his cells.” Nezuko wrapped her arms around Tanjirou, pulling him close as if it would protect him. As if she could possibly hope to shield him from Kibutsuji’s sick plan.
We’re so close to it being over, and Kibutsuji might take Tanjirou away and make it all for nothing. Nezuko thought while Tanjirou returned her embrace. A part of her wondered if he was just returning affection, oblivious to the threat to his life. Or perhaps he had picked up on her fear of losing him, and was trying to reassure her that he was still there.
“But there is other news I wish to share.” Tamayo added, turning to Yushiro. “If you could please see if you can locate Lady Kochou, Yushiro?” He bowed before leaving the room, leaving the other three to their devices. “I’ve been running tests on Tanjirou’s cells. Specifically in regards to how they react to Kibutsuji’s. And, from what I’ve seen, Tanjirou’s cells actively attack Muzan’s. It’s a strange phenomenon, not even my cells will do that to such an extent.” she explained, her gaze lowering to Tanjirou as he drifted off.
“What about your guess about him being like Kibutsuji? A demon progenitor?” Nezuko asked.
“It would seem my guess was slightly exaggerated.” Tamayo admitted with a small smile. “But it was only a guess. His cells attack Muzan’s, but Tanjirou cannot create his own demons with just his blood. I did run tests on human blood samples to be sure. With more time and power, he possibly could, but our goal is not for that.”
“Mhm.” Nezuko nodded.
“Amidst all the worrying news, however, there is some good to be found.” Tamayo’s smile gained a faint edge to it. “With Lady Kochou’s help, and Tanjirou’s blood, we have a serum that could help to destroy Kibutsuji for good. And thanks to the blood samples you and your Hashira friends have sent me, I’ve almost hit a breakthrough on a cure.”
“You have?!” Nezuko gasped. “How much longer do you think you’ll need?”
“No more than a few months. Possibly less, with Lady Kochou’s assistance. And the second I have a viable cure manufactured, it will be administered to Tanjirou. The man you helped in Asakusa will be receiving a second dose, and a third will be saved for Muzan.” Nezuko smiled at that, looking down to her sleeping brother.
“You’ll be human again soon.” Nezuko whispered, turning back to Tamayo. “Thank you, Miss Tamayo. I… I don’t have the words to tell you how grateful I am for all you’ve done for us.”
“All because of your help, Nezuko. If anything, I owe you my thanks. If not for you and Tanjirou, I’d still be hiding from both Muzan and the Demon Slayers, and getting nowhere close to a cure.” Tamayo countered. “Things have been set in motion, and the deciding battle is approaching. You’ll need to be ready, if you wish to defeat the remaining Twelve Kizuki and Muzan.”
“I’m sure we will be.” Nezuko replied with a smirk. Tamayo nodded with a sharp smile of her own, then stood up and left the room.
“Get back here!” Sanemi yelled as the demon jumped. However, when Sanemi followed it, he was met with a familiar sight.
Kamado, running for Shinobu and Upper Five.
The ground vanishing underneath their feet, being replaced by a maze of endless halls.
The mad dash from him, Kanao, and Shinobu to catch Kamado before she fell into the strange fortress.
The same place. Sanemi realized as he and Obanai descended. But unlike the last time Sanemi saw the place, it was crawling with demons. It couldn’t be the remaining Twelve Kizuki, there were too many of them. Sanemi raised his sword, ready to decapitate at least the nearest demon. But before he could, the ground returned to normal. “Damnit!” he spat as his sword stabbed the grass. Sanemi sat down, glaring at the ground while Obanai landed beside him.
“What was that?” the Serpent Hashira hissed.
“I don’t know, exactly, but I’ve seen it before.” Sanemi muttered. “When Kamado ran off, that place showed up. She almost fell in while we were fighting Upper Five.”
“I’m not the only one who heard a biwa when it disappeared, was I?” Obanai asked, Sanemi looked at him, more than a little confused.
“Yeah. Barely, but I heard it. What’s that gotta do with the creepy ground fortress?” Sanemi replied.
“When I was on assignment with Nezuko, we got ambushed by a large group of demons. She mentioned hearing a biwa whenever more showed up.” Obanai explained. “There may be correlation, if we heard it when that place vanished.”
“This is gonna be one hell of a report.” Sanemi sighed.
“Are you sure you should be eating so much after being unconscious for a week?” Goto asked. Nezuko turned to him, swallowing her mouthful of anpan before replying.
“I’m starving.” she replied, wiping up some of the bean paste on her cheek. “I’m trying to take it slow, though, I promise.” she added. Goto sighed, turning to the window.
“How has your brother been doing?” he asked. “It’s been kind of weird, seeing a demon outside in the daylight.”
“Yeah, but he’s really happy to play outside with the younger girls.” Nezuko told him. She turned to the window, spotting Tanjirou running around with Kiyo, Sumi, and Naho. So long as the sun is up, Kibutsuji can’t get him. Nezuko assured herself. How ironic, that the very reason Kibutsuji was trying to capture her brother was the very same reason he was safe from the Demon King. And hopefully, Kibutsuji would never find the Butterfly Mansion.
“Kamado Nezuko.” a deep voice spoke up. Nezuko turned around, meeting the wide blue eyes of the Kasugai Crow next to her. “My apologies for startling you, young lady. I am the personal messenger of Ubuyashiki Kagaya.”
“Oh!” Nezuko exclaimed as the crow’s piercing gaze remained on her. “Hello. What brings you here?” she asked as the crow perched on the head of Nezuko’s bed.
“I come to you with information and questions from Master Ubuyashiki. In the Swordsmith’s Village, a few of the villagers mentioned something odd about you, Lady Kanroji, and Lord Tokito. Lady Amane will be discussing it with the two of them during the Hashira meeting, but Master Kagaya and Lady Amane set me to attain your account first.” the crow told her. “The villagers informed them that you three developed odd marks during your battles against Upper Four and Five. Marks bearing resemblance to demonic crests.”
“Oh.” Nezuko replied, remembering the warm-almost-hot sensation that had raced across her forehead during the fight. “I didn’t realize that that was what that was. What is it, exactly?”
“Information is still being investigated, but as far as we know, it is called a Demon Slayer Mark. It has not been seen in the Corps since the Sengoku Era, when Demon Slayers first began using Breathing Styles.” the crow answered. “However, there has been no record of how it’s achieved. We were hoping one of those who had gotten one would have some sort of information about such a feat.” Nezuko hummed in response to the statement, thinking back to her most recent fight and the final moments of the fight in the Red Light District.
“Miss Aoi mentioned I had a serious fever. My body temperature was thirty-nine degrees Celsius, according to her. I think that’s over a hundred in Fahrenheit? And I remember my heart going really fast. I don’t know exactly how fast, but faster than I’d ever felt it go before.” she told the crow. “I actually think I manifested it in the Entertainment District, too. I felt a warmth across where my scar is, along with my heart racing. Right before Uzui and I decapitated Upper Six.” she noted, partially to herself. “Both situations where I think it manifested were high-adrenaline situations. And I feel like I shouldn’t have survived them.”
“I see. So you are the first Slayer in centuries to unlock the Demon Slayer Mark. I will pass this information to Lady Amane. Thank you for telling me, Miss Nezuko.” the crow replied. “With this information, perhaps we can come closer to defeating Kibutsuji Muzan.”
“I hope so.” Nezuko muttered as the crow bowed his head. “Please send my best wishes to the Master and his family, if it’s not too much trouble.” The crow nodded in response. Nezuko bowed to the crow, watching it fly away with a pensive pout on her face. Nezuko leaned back until she was resting on her pillow. Now that I think about it… Didn’t that man I saw in the inherited memories have a weird mark on his face? she wondered, running her fingers over her scar.
“Nezuko!” Everyone in the courtyard turned to the familiar voice, finding Zenitsu running up to them with a bright smile.
“Hey, take it easy! She has a broken foot!” Aoi snapped. Once he was close enough, Zenitsu scooped up Nezuko. It caused her to drop her crutch, but she didn’t mind. Zenitsu spun around with her in his arms, and Nezuko couldn’t help laughing.
“It’s so good to see you! I missed you so much!” Zenitsu exclaimed as he put Nezuko down, turning to the demon beside them and doing a double take. “Tanjirou?! He’s in the sun?! How?! Is he… No, his sound is still demonic!” he said, his eyes flicking from one sibling to the other as he gaped.
“We don’t know for sure.” Nezuko giggled as she got her crutch back in place. “But it’s good to see you, too. Welcome back.” she added, giving Zenitsu a gentle hug with her free arm.
“We… Wel…” Tanjirou spoke up, causing Zenitsu to gape again.
“And he can talk, too?!” he gasped.
“Aside from having to relearn words, yes.” Nezuko replied.
“Welcome back, Inosuke!” Tanjirou declared with a bright smile, clearly proud of himself. Zenitsu released a strangled sound, and Nezuko snorted before she burst out laughing.
“I’m sorry! I shouldn’t laugh!” Nezuko gasped between her laughs. She covered her mouth, trying in vain to stifle the laughing fit. Once she could finally stop, she turned to her brother and Zenitsu. “Inosuke’s spent the last little while teaching Tanjirou his name. He probably thinks everyone is Inosuke right now.”
“No!” Tanjirou protested indignantly, looking at Nezuko with the most offended face she had ever seen from him. Then he patted her head. “Nezuko!” He turned to the butterfly girls. “Kanao!” he declared, patting the head of the girl in question. “And… pink hair… Mitsuri! And then… funny haircut… Genya!”
“Who’s Genya?” Zenitsu asked.
“That guy with the mohawk.” Nezuko answered. “The one whose shoulder I dislocated after Final Selection. He’s actually not bad, we became friends during the mess in the Swordsmith’s Village. After Tanjirou tried to gouge his eyes out.” That got a nervous glance from Zenitsu.
“How bad is it?” he asked quietly.
“Oh, he’s fine. Didn’t even leave a scar.” Nezuko told him. “He has this crazy ability. Apparently eating demons can give him demon powers for a little bit of time.”
“Wow.” Zenitsu chuckled. “Sounds like you had a really crazy time.”
“Oh, yeah, it was insane.” Nezuko giggled. “But we killed two Upper Kizuki, apparently! Genya, Mitsuri, Tanjirou, and I took out Upper Four, and the Mist Hashira took out Upper Five! And Tanjirou can be outside during the day again.” She turned to her brother with a small smile, then grabbed his ear and pulled him towards her. “And someone decided to give me a heart attack and nearly die on me.” She knew it wasn’t his fault, but she still went through way too much stress to be dealing with before she was fifteen years old.
“Sorry.” Tanjirou mumbled while Nezuko released his ear.
“I know you are.” Nezuko sighed with an exasperated smile, turning back to Zenitsu. “How about you teach him your name? Then he won’t be as likely to call you Inosuke.”
“Sounds good.” Zenitsu replied. “Let’s go, Tanjirou.” he said as he made his way to the Butterfly Mansion with the demon in question right behind him.
“Okay, Boss Inosuke!” Tanjirou declared, earning another snort from Nezuko before the two boys disappeared into the Butterfly Mansion.
“You want to learn the other original Breath Styles?” Shinjurou asked. Nezuko nodded in response.
“Yes.” she answered. “I need to master Hinokami Kagura, but I don’t have a reference for what I might be messing up. If I learn the other Breath Styles created from it, maybe I can figure out what I have to fix. I’ve already started with Flame Breathing, actually, and I’ve improved a couple forms!” Shinjurou nodded, staring at the floor pensively.
“Well, I know all but one of the first five Breath Styles after Sun Breathing have a Hashira right now, and you already know Flame Breathing.” he replied. “We can send a request to the active Hashira, see if they’re willing to teach you their Breath Styles.”
“Which Breathing Style doesn’t have a Hashira?” Nezuko asked.
“Of the originals? Thunder. But the last Hashira’s only retired, so I--”
“Thunder Breathing?” Nezuko cut in. “I have a friend who knows it. Maybe I can ask him. I think he said he trained under an ex-Hashira.” Shinjurou stared at her with wide eyes.
“Must be one of Kuwajima’s students, then.” he muttered. “I’ll still send a letter to him, but you’re free to ask your friend when you see him next.”
“I’d really appreciate that.” Nezuko replied with a smile. Shinjurou nodded, and they both grabbed a sheet of paper and a pen. Two Kasugai Crows perched on the windowsill behind Nezuko, both of which she recognized. “Hi, Kaname. Hey, Tennouji.” she chuckled as she signed off her letter.
“Kaname? Aren’t you supposed to be with Kyojurou?” Shinjurou asked.
“Lord Kyojurou is at the Hashira meeting, Lord Shinjurou. And he requested I come to the Butterfly Mansion and check on Lady Nezuko.” Kaname replied, getting a huffy squawk from Tennouji.
“Kamado Nezuko is my Slayer!” he scoffed.
“It’s fine, Tennouji. We have jobs for both of you, anyways.” Nezuko told the corvid as she folded up her note to the Hashira. “Tennouji, I need you to get this letter to the Ubuyashiki Mansion, please. It’s technically for all the Hashira, but mostly Shinazugawa, Tomioka, and Himejima.”
“Understood!” Tennouji squawked, taking the letter and flying off.
“Kaname, I need you to find Kuwajima. Give him this.” Shinjurou told Kyojurou’s crow, tying the letter to the other bird’s leg and letting him take off.
“I hope this plan works.” Nezuko muttered. I wonder how the meeting is going.