"This is someone else's home, you can't be so willful, Tanjiro is right next to me, darling!"
Ryuya rubbed Makomo's head, intending to use those words to make her give up her plan.
Unexpectedly, Makomo raised her flushed face and breathed warm air against him. "Doesn't that make it even more exciting?"
"Exciting your head!"
Startled, Ryuya flicked her forehead, then quickly stood up, grabbed the Nichirin Blade by the door, and stepped outside.
"Seriously!"
Makomo, dark circles under her eyes, pouted resentfully and followed closely behind Ryuya like a lingering spirit.
After leaving the house and putting some distance between himself and Kamado Tanjiro's home, Ryuya found an open clearing and drew his Nichirin Blade.
Makomo, unable to sleep, had secretly followed him and crept closer.
Still unwilling to give up, she asked tentatively, "Master, you said we can't be willful in someone else's home, so when we're in our own home, can Makomo do whatever she wants?"
"Still thinking about nonsense? Stop messing around and don't disturb Master's important business, I need to practice my sword!"
"Hey, hey, hey, Master, your Nichirin Blade still looks so fierce!"
Makomo squatted down, resting her chin in her palms as she stared at the blade.
At first glance, it looked similar to an ordinary Nichirin Blade, but the material was completely different. The surface was covered in eye-like patterns, strange and unsettling, enough to make anyone's scalp tingle.
"Speaking of which, Master, your Nichirin Blade was given to you by your own Master, right?"
Curiosity and longing sparkled in Makomo's eyes. "After all these years, I've never met the Grandmaster who taught you Moon Breathing. I'm really curious, what kind of person is he?"
Ryuya chuckled softly. "So curious? If there's a chance, I'll take you to meet him."
He believed his Master, Kokushibo, would be pleased to see Makomo. After all, she was adorable. Who wouldn't like her?
"Then it's a promise, Master!"
Makomo extended her pinky.
When she was little, they used to seal promises like this. Once pinkies were linked, no one was allowed to go back on their word.
"Alright, alright, pinky promise."
Ryuya hooked his finger with hers, then lifted his blade and began recalling the Hinokami Kagura that Tanjiro had performed earlier that night.
Under the effects of the Transparent World, his memory was so vivid it felt as if Tanjiro were dancing right before him again.
Ryuya followed the rhythm in his mind and began attempting Sun Breathing.
Makomo stayed quiet. She was sensible enough not to interrupt, simply squatting to the side and watching.
As she observed, her pupils suddenly contracted.
If she wasn't mistaken, wasn't Master performing the Hinokami Kagura that Kamado Tanjiro had just danced?
Shock filled her heart, but she remained silent.
When Master had first taught her sword techniques, he had been just as serious and meticulous.
Serious boys really are the most attractive.
Makomo watched with fascination.
But just as her interest peaked, Ryuya abruptly stopped.
"Master?"
Makomo sprang to her feet, her pupils shrinking in alarm as she rushed forward.
Something was clearly wrong.
"Cough, cough!"
Ryuya felt a burning pain tear through his lungs and instinctively covered his mouth.
When he pulled his hand away, bright red blood stained his palm.
"Master!"
Makomo grabbed his hand, and upon seeing the blood, her body trembled even more violently than his.
She looked up at him anxiously. "Master, are you sick? What's happening?!"
"It's nothing, don't worry."
"But—"
Despite the concern clouding Makomo's moist eyes, Ryuya stood up again.
He attempted Sun Breathing once more, stubbornly refusing to stop.
The Nichirin Blade cut through the air as he drew in a deep breath.
This time, it was even worse.
A scorching heat ignited inside his abdomen, as if his internal organs were being incinerated from within. The pain forced him to spit out another mouthful of fresh blood.
The blade stabbed into the ground. Ryuya leaned on it for support, switched to Moon Breathing, and inhaled deeply to stabilize himself.
A Breathing Technique was not only for combat. When mastered and used alongside sword forms, it could regulate the body, soothe pain, and accelerate recovery.
After several steady breaths, the burning sensation gradually subsided.
"Master, is it because of the sword technique you just performed?" Makomo asked carefully.
"Yes."
Ryuya lifted his head and stared at the moon, now half-veiled by drifting night mist. A deep unwillingness surged within him, his clenched fists betraying his frustration.
After this second attempt, he finally understood the issue.
It wasn't his movements.
It wasn't his footwork.
The problem was Sun Breathing itself.
As a demon, when Ryuya used other Breathing Techniques—most notably Moon Breathing, second only to Sun Breathing—there had been initial awkwardness, but never rejection from his body.
But Sun Breathing was different.
His demon body was rejecting it.
Sun Breathing was the original Breathing Style, the first and strongest technique created specifically to kill demons. It inherently suppressed demonic existence.
When Ryuya attempted to use it, the scorching energy coursed through him like wildfire, burning his organs and searing his veins.
It felt nothing like the smooth, cold comfort of Moon Breathing.
The contrast was extreme.
So was he supposed to give up?
Was there truly no other way?
Ryuya gazed at the moon, now obscured almost entirely by mist.
Just like his future—unclear and unknowable.
Danger lurked everywhere. Though his current strength was not weak, he was still inferior when compared to Kokushibo and Muzan.
Danger thrives in weakness. When one becomes strong enough, danger fades on its own.
If he wanted to eliminate threats before they manifested, he had to grow stronger.
And the most direct path forward was Sun Breathing.
Ryuya refused to let such an opportunity slip away.
It was painful.
It was difficult.
But he could endure.
What doesn't kill you only makes you stronger.
He would not give up so easily.
...
Author's Note:
The full completed version of Demon Slayer: Son of Muzan (Completed) is now on Patreon!
🔥 I also have additional 18+ fanfics available for readers who enjoy exclusive mature stories. 😉
1. Dragon Ball: Oolong's Sex Adventure
2. Elements of Lust – ATLA & Korra Mixed Smut
3. Doraemon: Filtering with Nobi Tamako
4. The Naive Me Who Became Someone's Everyday Secret
5. High School DxD: Rias Gremory, the Phenex Bride
6. Versatile Mage: Awakening the Succubus System
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