Dust rose across the training field as a powerful gust of wind swept through. The pale green aura of Wind Breathing clashed with the golden glow of Sound Breathing, producing a sharp, rhythmic ringing of "clang, clang, clang."
Shinazugawa Sanemi and Uzui Tengen stood opposite each other, wooden swords in hand. Their movements were so fast that only afterimages remained, and every strike split the air with a violent hiss. Even the surrounding atmosphere seemed to shudder from the force of their blows.
"Wind Breathing, Sixth Form: Black Wind Mountain Mist!"
Sanemi roared, swinging his blade downward. The wooden sword carried a spiraling current of fierce energy that sliced toward Tengen's chest. Pale green wind blades gathered around the edge, scattering pebbles across the ground. Even the trainees watching from a distance could feel the sharp pressure of his killing intent.
But Tengen didn't flinch. The golden aura of Sound Breathing rippled beneath his feet, forming an invisible score line. Moving with perfect rhythm, his body danced between the gaps of the whirling wind blades, every step landing like part of a grand performance.
"Sound Breathing, Fourth Form: Constant Resounding Slashes!"
His wooden sword moved with musical precision, golden arcs vibrating like plucked strings. Each motion blocked Sanemi's attacks perfectly before he used the recoil to slide back three steps, narrowly dodging Sanemi's sweeping follow-up strike.
From the sidelines, Inosuke, Zenitsu, and Tō watched intently.
Before their training with the Hashira, they wouldn't have been able to follow even a fraction of the movements before them—only blurs of color and motion. But now, their perception had sharpened drastically.
They could see that before every strike, Sanemi's shoulders dipped slightly, signaling his intent.
They could sense that every dodge from Tengen followed a precise rhythm, his movements aligned to a repeating beat pattern. They could even guess their next moves.
"So fast! Shinazugawa-san's strikes are brutal, but Uzui-san's dodging them all!" Zenitsu said in awe, gripping his own wooden sword as sweat beaded in his palms.
He could feel the difference—Sanemi's Wind Breathing overflowed with raw power, while Tengen's Sound Breathing emphasized technique and timing. Their styles couldn't be more different.
Inosuke clenched his fists, his eyes blazing. "Amazing! If I had that kind of speed, the next time I meet that spiky-haired bastard, I'll slice him for sure!"
Tō, standing beside them, analyzed quietly. "Shinazugawa-san's attacks follow a suppressive rhythm—every third strike is a power burst. Uzui-san's style is rhythmic—he uses his score to read the opponent's tempo and adjust his breathing for counterattacks."
Just as Tō finished speaking, Sanemi suddenly accelerated.
"Wind Breathing, Ninth Form: Idaten Typhoon!"
His wooden sword howled downward with unstoppable force, the air itself tearing apart under the strike. It was one of Wind Breathing's killing forms—twice as fast as before, leaving no room to dodge.
Every watching trainee held their breath. Even Zenitsu gripped his uniform nervously—
there was no way to evade that slash.
But Tengen only grinned. His golden aura flared brighter. "So you're serious now, Sanemi? Don't forget—my score's not just for dodging!"
Instead of blocking, he suddenly changed rhythm, sliding sharply to the left. His wooden blade traced a brilliant golden arc across the ground—
a new score node he created on the spot, based entirely on Sanemi's attack pattern.
Sanemi's blade missed by a hair's breadth, striking the ground with a crash that sent dust flying.
In that same instant, Tengen's sword stopped at Sanemi's waist—only an inch away from "striking."
"You're out."
Tengen straightened, withdrawing his weapon as his golden aura faded. Sweat trickled down his temple. "Your final strike was too rushed. Your rhythm broke—I saw it coming long before you swung."
Sanemi paused, then clicked his tongue and sheathed his sword. "Tch. Next time, I won't give you that chance."
His voice was curt, but there was a spark of respect in his eyes. He knew Tengen's musical score was extraordinary. To predict and exploit an opening during his strongest attack—it was no small feat.
"Hahaha! Anytime!" Tengen laughed heartily, clapping Sanemi on the shoulder before turning to the trainees.
"Did you all catch that? Fighting isn't just brute force—it's rhythm and prediction. Find your opponent's weak point. That's far more important than blind aggression!"
The trainees nodded eagerly. Inosuke bounded forward. "Hey, white hair! Teach me that score thing! I wanna move like that!"
Tengen chuckled and waved him off. "Patience. Master your breathing rhythm first. Once you can keep tempo, we'll talk about scores."
He turned toward the exit. "I'll check on Kanae's group next. Keep practicing!"
Sanemi wiped the dust from his sword and looked toward Tō. "Tō, your Storm Breathing isn't so different from Wind Breathing in principle. When there's time, we'll spar."
Tō blinked, then nodded firmly. "Yes, Shinazugawa-san!"
Without another word, Sanemi strode out of the field.
Inosuke and Zenitsu immediately surrounded Tō, bursting with excitement, replaying every detail of the spar they'd just seen. All three of them shared the same fire in their eyes—a burning drive to grow stronger.
…
Meanwhile, behind the Butterfly Mansion, a smaller training ground sat bathed in late afternoon light.
Kocho Shinobu stood alone, gripping a slender wooden blade as she practiced her thrusts. The faint lavender aura of Insect Breathing gathered around the sword, forming flickering insect-shaped shadows that danced through the air with each motion.
Her arms ached with exhaustion, her muscles trembling. Sweat streamed down her face, dripping onto the wooden floor and staining it darker with each drop.
Still, she didn't stop. She adjusted her breathing rhythm again and again—
each inhale condensed energy into her core,
each exhale guided that flow into her blade, sharpening and quickening every thrust.
Ever since her sister, Kanae, was injured in the battle with Mushiki, Shinobu had made up her mind—she would no longer stay behind as support.
She needed strength. She needed to stand at the front lines beside the other Hashira and protect those she cared about.
"Insect Breathing, Butterfly Dance: Teasing!"
Her voice was steady as she struck. The wooden blade flashed five times in an instant, the greenish insect shadows darting forward like venomous bees.
Each hit struck perfectly on the two red dots painted on the training post—marks simulating a demon's vital points.
It was a technique she had developed herself, inspired by Kanae's Flower Breathing.
Where Flower Breathing focused on wide, sweeping movements, Shinobu's Insect Breathing emphasized pinpoint precision and speed—perfect for dealing with agile demons.
"Still not fast enough."
Shinobu frowned, staring at the red dots on the training post.
The second strike had been 0.4 seconds slower than the first. Against an Upper Moon, that 0.4 seconds would be enough for the enemy to dodge.
She took a deep breath and recalled her sister's voice: "Your breathing must be delicate, not hurried. Let your breath wrap around the blade like fine silk..."
Shinobu adjusted her breathing again—this time without using full force, letting the air flow gently through her body.
Her wooden sword darted forward once more. "Insect Breathing, Butterfly Dance: Teasing!"
The five thrusts struck almost simultaneously. Pale violet insect shadows crossed each other midair, leaving twin shimmering trails that overlapped perfectly.
A faint smile touched her lips. The ache in her arms seemed to ease a little.
"Shinobu, take a break."
Kocho Kanae's gentle voice came from nearby as she approached with a cup of warm water. "You've been training for two hours. Keep this up, and you'll strain your arms."
Shinobu paused, accepted the cup, and sipped slowly. "Nee-san, I want to get stronger. I don't want to keep watching everyone get hurt while I can't do anything."
Kanae stroked her sister's hair softly, her eyes full of warmth. "I know. But strength doesn't come all at once—it takes time.
Your Insect Breathing has already grown powerful. You've progressed faster than I did when I first learned Flower Breathing."
She glanced at the wooden sword in Shinobu's hand. "Besides, your strength isn't just your sword.
The medicines you've developed—those that stop bleeding, neutralize poison, and even boost Breathing techniques—those are powerful too, aren't they?"
Shinobu blinked, then nodded slightly.
She remembered the report she had received from the Kakushi the day before:
The Breathing Amplifier she created could temporarily boost a user's Breathing technique by ten percent with minimal side effects. It was already being distributed among lower-ranked slayers.
"I'm still developing a new formula," Shinobu said, setting down her cup, her eyes firm with resolve.
"I want to merge the blood of a Lower Moon demon with the medicine. If successful, the user could temporarily gain the precision of Insect Breathing—making it easier to strike a demon's weak points during battle."
"That's a brilliant idea!" Kanae's eyes brightened. "If you need help, come to me anytime. I can test the medicine's effects on Breathing techniques."
Shinobu smiled, feeling her determination ignite again.
She gripped the wooden sword tightly, the soft violet aura of Insect Breathing gathering once more. She knew that every small improvement—whether in swordsmanship or in medicine—brought the Demon Slayer Corps closer to victory.
Just then, a Kakushi came running up the path, holding a sealed letter. "Kocho Shinobu-sama! Kocho Kanae-sama!
Oyakata-sama requests your immediate presence at Headquarters. It's urgent—something about the northern region!"
Shinobu and Kanae exchanged a quick glance. Both saw the same concern in each other's eyes.
The northern region—Tanjiro's territory. Could something have happened?
"We're coming at once," Kanae said, putting the cup aside and taking Shinobu's hand. The two sisters hurried toward Headquarters.
Behind them, the slender wooden sword still stood beside the training post. The faint violet glow that lingered on the blade shimmered softly, like it carried the thoughts left unsaid.
Inside the meeting hall, Ubuyashiki Kagaya sat at the head of the long table. The other Hashira were already assembled.
Tanjiro stood beside him, holding a report, his face grave.
"Recently, in the northern region, multiple demon attacks have occurred," he began. "The traces left behind carry faint demon energy—
and all the bodies show signs of being crushed by something resembling a water vortex. It may be connected to Mushiki."
Kagaya's voice was calm but commanding. "I called everyone here to discuss the northern defense plan.
Reports from the Kakushi say demon activity there has increased. They haven't attacked villagers directly yet, but they seem to be watching… searching for something.
I fear the northern villages may soon be in danger—and so might our slayers."
"I'll go!"
Sanemi was the first to step forward, his wooden sword gripped tight. "I've been wanting to face that traitor again. This time, I'll cut him down myself!"
"I'm coming too," said Tengen, standing up beside him.
Kanae and Shinobu exchanged a look and nodded. "We'll go as well," Kanae said. "My Flower Breathing can provide support, and Shinobu's medicine can handle bleeding and poison."
Kagaya smiled faintly. "Good. Then Sanemi, Tengen, Kanae, and Shinobu will depart tomorrow morning. You'll meet with Tanjiro and travel together to the north.
The remaining Hashira will patrol the other regions to prevent any further demonic disturbances."
"Yes, Oyakata-sama!" they all answered in unison.
After the meeting, Shinobu and Kanae walked back toward the Butterfly Mansion, their shadows long beneath the setting sun.
"Shinobu," Kanae said softly, "do you really think Mushiki… do you think Giyu would hurt the villagers?"
Her tone carried a trace of worry. She remembered the old Giyu—stern-faced, quiet, but with a deeply gentle heart.
Shinobu was silent for a moment before shaking her head. "I don't know. But whoever he is now, we still have to protect the villagers… and maybe—find a way to bring his memories back."
Kanae nodded, saying no more. The two sisters walked side by side, both knowing that the journey to the north would not be easy.
…
Night deepened. The Butterfly Mansion glowed softly under the lamps.
Shinobu sat in her laboratory, holding a vial of pale violet liquid—the newest version of her Breathing Amplifier. It could grant the user power approaching that of a demon.
She carefully sealed the vial inside a small case, her expression calm but resolute.
This time, when they went north—she would use this medicine herself.
Together, they would find Giyu… and bring him back.