Tomioka Giyu woke to the cold.
The sky outside was still pale, just a faint strip of dawn light outlining the roof's edge.
Inside, the charcoal fire had burned low, leaving only a thin warmth. The air carried the crisp, biting chill of early morning.
He sat up, rubbing his stiff shoulders. The exhaustion from yesterday's mountain training still clung to him.
Just as he put on his haori, he heard a soft sound outside the door.
Sliding it open, he saw Kamado Tanjuro standing in the yard, his back to him, gazing toward the east.
The man wore only a thin kimono, and a layer of frost covered his shoulders as if he had just come in from the snow.
When he heard the door, Tanjuro turned, smiling warmly, his breath steady despite the cold. "You're awake."
"You woke earlier than me, Kamado-san."
Giyu stepped forward, noticing the faint red flush on his cheeks and the purplish tint to his lips.
"I'm used to it," Tanjuro said with a soft laugh, followed by two quiet coughs that rasped in his throat. "I used to go up the mountain before sunrise to cut wood. Once the snow melts, the path gets slippery. Even now, I still wake at the same time—it's a habit I can't break."
Giyu said nothing. He could see the toll the cold took on Tanjuro's fragile body. Just standing here must already be painful.
"Come," Tanjuro said, walking toward the open space in front of the house.
The snow there had been swept aside, revealing the frozen earth beneath.
Giyu followed, hesitant.
The morning air felt like an ice cave—wind cutting across his face like blades. Every breath turned to white frost the instant it left his lips.
The chill crept up from his ankles, numbing even him.
"Kamado-san," he said, frowning, "it's too cold outside. Maybe we should wait until the sun rises a bit?"
Tanjuro stopped and turned to him.
His face was pale, bloodless, but his eyes shone with quiet resolve.
"It's fine," he said gently. "The Dance of the Fire God is meant to be performed at dawn. The air now is cleanest—and your heart, most still."
He smiled again, that same calm smile that eased the tension in others. "Don't worry. I know my limits."
Giyu said no more.
He could tell—once this man made up his mind, nothing would move him.
Tanjuro stepped to the center of the yard, then turned to face him.
"Tomioka-san, watch closely," he said, his tone serious now.
"When I perform the Dance of the Fire God, don't just watch my movements. Listen carefully to my breathing. Every motion has its rhythm. Without breath, the movement dies."
Giyu nodded, holding his breath, his full attention fixed on the man before him.
He knew what he was about to see might be the most coveted secret in all of the Demon Slayer Corps—the origin of every Breathing Style.
Tanjuro inhaled deeply.
The breath filled his chest completely. Even through the cold air, Giyu could hear the faint sound of air drawing into his lungs.
Then, Tanjuro moved.
No exaggerated stance, no dramatic flourish.
The motion was simple—almost plain.
His right foot slid forward a step, knees bending slightly, his right hand curling as though holding an invisible blade. He drew it upward slowly, tracing an unseen arc.
"Haa—"
With the motion came a long, steady exhale—soft and even, like wind gliding through the bamboo of the mountain.
Giyu's pupils constricted.
This movement—he'd seen something like it before.
It was the foundation of Sun Breathing: Hinokami Kagura, First Form – Dance. Yet when performed by Tanjuro, it felt completely different.
It didn't burst with force—it flowed, harmonizing perfectly with the air around him, the ground beneath, and even the snow-capped peaks in the distance.
Then Tanjuro's movements quickened.
He stepped lightly across the frozen ground—advancing, retreating, turning.
Every movement was clean, every gesture fluid.
His right hand drew sweeping arcs, at times rising like flames, at times falling like water, and at times circling endlessly like a sun in motion.
Those were the forms of the Dance of the Fire God—the twelve Sun Breathing forms.
Giyu tried to recall their names—"Clear Blue Sky," "Burning Bones, Summer Sun," "Sunflower Thrust"—
But he stopped trying.
Because Tanjuro's dance had no beginning or end. Each form melted into the next, one flowing into another seamlessly, as if the entire sequence was meant to be one unbroken whole.
What stunned him even more was Tanjuro's breathing.
No matter how fast he moved, his breathing never faltered.
Every inhale was long and deep; every exhale smooth and measured.
The rhythm was perfect—each breath spaced precisely, like the steady beat of an invisible drum guiding every motion.
Even during the wide, powerful swings that demanded strength and stamina, his breathing never wavered.
It was like watching stillness inside motion—silence within the storm.
Giyu stood frozen, eyes wide, barely able to breathe himself.
This was nothing like he had imagined.
He had thought Sun Breathing would be like Rengoku-san's Flame Breathing—fierce, blazing, overflowing with explosive strength—or perhaps like his own Water Breathing, flowing endlessly with quiet persistence.
But what Kamado Tanjuro displayed was something entirely different—extreme simplicity and perfect balance.
No wasted energy. No forced momentum. Every ounce of strength was placed precisely where it belonged—on the blade, even if that blade was only imagined.
Every breath supported the motion in flawless harmony.
This wasn't mere swordsmanship or a breathing technique. It was something deeper—like his body was resonating with the world itself.
And his stamina…
Giyu watched as Tanjuro repeated the entire sequence again and again in the snow-cleared yard.
Once. Twice. Three times.
Sweat soaked through his thin kimono, running down his face and freezing at his chin into tiny beads of ice.
His breathing began to grow ragged, his face turned even paler, and at one turn, his body wavered dangerously.
But he didn't stop.
It was as if an invisible force sustained him, keeping his movement precise and his breathing steady even as exhaustion consumed him.
The pale dawn sky deepened into a faint gold—the sun was about to rise.
The wind softened. Sunlight pierced through thin clouds, spilling across the ground, wrapping Tanjuro's figure in a gentle glow.
His movements in that light looked clear and sacred—every turn, every sweep of his arm seemed to speak directly to the newborn sun.
Then, just as the first edge of sunlight touched the horizon, Tanjuro stopped.
He froze in his final stance—right hand raised high, body leaning slightly back, as though to embrace the rising sun itself.
Sweat dripped from his hair, glimmering like glass in the morning light.
He panted heavily, chest rising and falling, his face white as paper, yet his lips were tinted with a strange, vivid red.
After a long moment, he slowly lowered his arm and turned to face Giyu.
The morning sun cast across his face, softening his pallor but making his eyes shine brilliantly—eyes that seemed to ask a silent question.
"Tomioka-san," he said quietly, yet his voice carried clear through the crisp air, "did you understand?"
Giyu stood motionless.
His mind was still replaying what he had just seen—the perfectly measured movements, the impossibly calm breathing, and Tanjuro's unyielding will that held firm even when his body was at its limit.
It was all etched into his mind like a seal.
Now he finally understood why Tanjiro once said his father could strike down a bear with a single punch.
The man before him, fragile as he seemed, carried within him a strength beyond understanding.
That strength didn't come from muscle or technique—it came from something deeper, something primal.
Perhaps this was what Tanjuro meant by "heart."
The essence of Sun Breathing wasn't in complex forms or dazzling power—it was in this perfect harmony between nature, breath, and self.
Giyu took a deep breath, forcing down the stir of emotion in his chest, and bowed slightly. "…I've only grasped the surface."
He wasn't being humble—it was the truth.
He could remember the movements, sense the rhythm of the breathing, but that inner resonance, that flowing heartbeat through every motion—he hadn't touched it at all.
Tanjuro smiled faintly, unsurprised. "That's normal. I've practiced the Dance of the Fire God my whole life, and even now, I wouldn't dare say I've mastered it."
He stepped forward and handed Giyu a folded towel. "Here. Wipe your face. You may not have moved, but standing in this wind will still freeze you through."
Giyu accepted it and realized his cheeks and ears were completely numb, his hands stiff from the cold.
"From tomorrow morning onward," Tanjuro said calmly, "follow exactly what I just did. Don't rush for speed or strength. Focus on precision—let your breath guide your movement.
When you feel your breathing and your body move as one, come find me again."
"Yes," Giyu said, nodding firmly.
The sun had fully risen now, spilling golden light over the yard, driving away the last of the night's chill.
In that glow, Tanjuro's shadow stretched long across the snow.
He still looked thin and frail, yet in that moment, all weakness vanished—what remained was quiet strength, born of endurance and grace.
Giyu watched his back and felt an unshakable certainty rise within him.
Perhaps coming to the Kamado household had been the most important decision of his new life.
He clenched his fists, feeling the warmth of the sunlight spread across his skin.