Chapter Text
Tanjiro blew on the gourd as hard as he could.
More… more! More until you can't blow anymore! More until your lungs feel like bursting! The clay gourd is enormous and hard and durable, but you have to push through! You are the eldest son, Kamado Tanjiro–!
He felt the gourd crack under his fingers… and then it burst from the force of his breaths. Tanjiro gasped with a big smile.
I did it!
Rengoku would be ecstatic! Rengoku would be proud! Tanjiro's training was bearing fruit! Weeks and weeks of swimming against the current of the freezing river! Weeks and weeks of strengthening his lungs! Finally, he was able to blow the biggest gourd wide open! Soon, he'd be able to keep up Total Concentration Breathing Constant all day. At the moment, he still struggled to keep it up while asleep, but surely that too–
"Tanjiro," Tomioka's voice called out from the engawa. Tanjiro turned his head to look at him curiously. Rengoku was still not here, so early in the morning, but Tomioka and Nezuko were training as usual. He wondered what he needed from him. He tilted his head in question.
Tomioka, already used to his wordless self, said, "Can you do me a favor? I need to demonstrate something for your sister."
Happy to help, Tanjiro stood up and hurried over.
Tomioka and Tanjiro stood facing each other in the courtyard, with Nezuko watching from the engawa with a determined gaze. On their hands they held wooden swords, and Tanjiro tightened his hold on his as he made a stance. Tomioka told him to attack him with one of his best widespread attack, and he knew just the one. Knowing the strength of the Hashira in front of him, Tanjiro didn't bother to hold back.
Hinokami Kagura, Fourth Form, he thought, Burning Bones, Summer Sun!
As the attack hurtled towards Tomioka, he said, unfazed, "Water Breathing. Eleventh Form: Dead Calm."
The entire attack seemed to simply pass through him. He stood there, unmoving, unharmed. No... he moved so fast he only seemed to be unmoving. Calm as the surface of still waters, he deflected every slash of Tanjiro's blade. A solid defensive manuever, no chinks in the armor at all- Amazing! An eleventh Water Breathing Form!
"I want you to master this move as well and put it in your arsenal," Tomioka told Nezuko. "Dead Calm is a personal creation of mine. Creating new forms is important so that Water Breathing would become stronger over time."
"A-Amazing," Nezuko said, still stunned.
"You have become a better Water Breather since I started training you," Tomioka continued. "But, for you to truly master this style, I want you to do the same as I did."
Tanjiro's eyes widened. Did he mean...?
"Kamado Nezuko," Tomioka said, meeting his little sister's eyes. "I want you to create a twelfth Water Breathing Form."
"A-A twelfth?" Nezuko looked immediately intimidated. Tanjiro understood. He himself had modified a form in the past, when he created Dancing Flash from Zenitsu's thunder breathing. But creating an entirely new form was a completely different ballgame. It required truly understanding the style you were using inside and out. A true form of Mastery. Tomioka was expecting this of little sister, and in a way, it must be both scary and encouraging for her. After all, the fact that he was making her do this at all showed that he believed in her, that he believed it was possible for her.
With the way Nezuko had been working so hard, Tanjiro believed she could do it, as well. He believed she could be a true Water Breathing Master. Walking closer with a skip in his step, he took her hands in his and smiled. "Nezu… work… hard."
Nezuko met his eyes and he could see the intimidation turned into determination. She squeezed his hand. "I will, Onii-chan."
His little sister was truly amazing. It was hard to think that two years ago, she was an entirely different person. But… maybe that wasn't true. Maybe Nezuko had always had this fire in her. He remembered the time in their childhood when she yelled at an adult for hurting a kid while they were in town. It scared their little siblings, but Tanjiro had always admired her for that. Both the gentle and patient Nezuko and this fiery and determined Nezuko could coexist inside his little sister. Tanjiro was starting to truly accept that.
He would continue working hard, too.
After that revelation, Rengoku arrived, proclaiming that he wants to take Tanjiro along with him for a mission. Now, this wasn't unusual. The two Hashira had been bringing them along on their missions to get more experience, sometimes together, sometimes on their own. Because they had met and defeated a Twelve Kizuki, Kagaya had expressed a desire for Tanjiro to be even more careful from now on, also from the advice of Lady Tamayo. To Tanjiro's disgruntlement, this meant only going outside of the estate with a Hashira present. At least Kagaya had heeded his wish that Nezuko did not go on any missions on her own, unbeknownst to his little sister. They truly were being treated with special attention. He hoped they weren't taking advantage of Kagaya's generosity…
With Nezuko busy trying to learn Dead Calm, Rengoku only took Tanjiro that day. They left the Water Estate as soon as the sun set. It was just a simple mission, so none of them were truly worried.
They made quick work of the demon who was terrorizing the train stations they went to. He was incredibly fast, but Rengoku was faster, able to corner him enough for Tanjiro to come in from above and take off his head. Ever since he started training, the necks of these low level demons had started feeling softer and softer- almost like butter- and it was fascinating how his demonic strength paired with his newfound breathing mastery was helping him out. He wondered how much his strength would decrease once he turns back into human, and decided that didn't matter right now.
Rengoku was grinning wide as he approached him. "Kamado-shounen! You are becoming even more and more impressive! Good work!
Tanjiro's heart fluttered at the praise. Rengoku had always given them with complete genuineness. He smiled widely at the man.
"It is good that the demon didn't manage to get any hostages. But we should still check upon those bento sellers, just in case."
Tanjiro nodded as the two of them continued walking. Those bento sellers- the old lady and her grandchild- were really nice. He was glad that they were safe. He'd hate for something to happen to them.
Ever since he became Rengoku's student, Tanjiro couldn't help but feel like he'd become a real demon slayer. He already was an honorary one from the beginning, but the way everyone treated him now, as if he was a real comrade and not just 'this one demon slayer's demon older brother'... it warmed his heart. The more missions he partook in with Rengoku , the more he could sense the regard in his eyes, and it felt good to make a man like Rengoku proud of him. Tanjiro wanted to be more useful. He wanted to help out as much as he could. That's why...
"Rengo...ku-san..." he started.
"Hm? What is it, Kamado-shounen?"
Tanjiro bit his lip. "I... want... to practice... my blood… demon art... on... demons." This had been on his mind for a long time now, but he didn't dare voice it out, worried that Rengoku would think it was a bad idea. He had only used his blood demon art once, while he was out of his mind. What if Rengoku thought that the blood demon art was too demonic to be cultivated? Would he think that it would lead Tanjiro to indulge his demonic side too much?
He waited, as Rengoku seemed to be deep in thought. Tanjiro was nervous, just wanting him to understand-- his blood demon art seemed to be powerful. If it could help them defeat more demons...
"Hm! That doesn't seem to be a bad idea. Especially as we start battling stronger and stronger demons in the future... But remember that the last time you did it, you lost control. Whether that was because of your injuries or because of the influence of the demon art remains to be seen, but we cannot be careless about this."
"My flames... don't... hurt... humans," Tanjiro said.
"That is true! And yet you still bit your friend. I am not against making use of the hand you're dealt, but I would be more comfortable if we test it first in a controlled environment."
That made sense. They can never be too careful.
"Let me think about this!" Rengoku said. "I will ask my fellow Hashira if they have ideas! Do not worry, I will help you reach your full potential, Kamado-shounen!"
Tanjiro smiled widely. For sure, Rengoku would figure it out. Rengoku, after all, never went back on his word.
The two of them continued walking to their destination in silence, unaware of the wind listening in.
The wind whispered the words into Mukago's ear, always her faithful servant. She had been tailing demon slayers all this time, trying to get some information on the demon that their Master told them to find. Finally, she had produced results. Finally, she had found him. The demon with the hanafuda earrings… She didn't know why he looked human, but it must be a trick. He talked about a Blood Demon Art, so it must be him!
She didn't know what to do.
Her Master had told them to expect a feral demon. One that was possibly restrained in one of the bases of the Demon Slayer Corps. But this demon was anything but that. In fact, he looked quite carefree, out and about, slaying his fellow kind with a nichirin blade. What kind of bullsh*t was that? A demon pretending to be human?
Mukago was so confused. It shouldn't matter, because all she needed to do was abduct him. It shouldn't matter, because once he was in their Master's grasp, he would fall back into his proper place. And yet, she couldn't do her orders, couldn't do her duty, all because of those damn Hashira...!
She followed him more over the past few days, tailed where he went as soon as the sun set. The demon boy never went out of the estate without a Hashira companion. And when he was inside the estate, the wisteria prevented her from sneaking inside. What a mess! Her chance to get her Master's favor was right in front of her, but it was so out of reach! She had been waiting for a chance, but there wasn't one at all! She knew that if she faced a Hashira, she would die. They were way too strong for a Lower Moon Four like her. But if she failed this mission for her Master, who knew what he would do! It was a lose-lose situation.
Unless... she sought help from a fellow Lower Moon...
Would they be open to it? Surely, they would. If they could just overpower the Hashira, there would be no problem. Sharing the credit wasn't ideal, but if it was to make sure she kept her own head...
Would two Lower Moons be enough for a Hashira? Would three? Four? She knew that the Hashira of this era seemed to be getting stronger and stronger than ever. If she could just gauge their power level, then she could make a better decision. But all the demons she saw fighting them were so weak! She couldn't afford to be wrong about this! She had to make sure that she survived!
There was one thing that assured victory. Enmu's Blood Demon Art could put these Hashira to sleep easily. But the sad*stic bastard was so full of himself. So confident of his abilities that he insisted they attack the Demon Slayer bases, and kill all the Hashira in their way! What a fool! As if he could do that! Mukago knew he was Lower Moon One, but the difference in skill was still too far!
But... if they plan it just right, perhaps the difference in skill wouldn't be a problem at all...?
She needed to consider this. She needed to plan. And above all...
She needed to contact her fellow Lower Moons.
