"What the hell even are you?"
Mitsuru stood on the opposite rooftop, his heart racing with that familiar thrill he'd been chasing his entire life. This was it—his first real demon. The danger was palpable, electric in the air, and every instinct screamed at him that one wrong move could mean death.
Perfect.
The demon before him was beautiful and monstrous in equal measure—a woman with elaborate hair decorations and obi sashes that moved like living serpents. But he schooled his expression into surprise and wariness. Can't let them know he has any idea what's happening.
"Another Demon Slayer? No, wait, are you a normal human?"
Daki's suspicious gaze scrutinized the figure on the opposite rooftop. He wasn't wearing a Demon Slayer uniform, and the sword in his hand—she could tell even from this distance—wasn't a Nichirin Blade. No sun-infused steel, no threat to her immortal body.
"How ridiculous!" Her beautiful face twisted into something monstrous, rage distorting her features. "A human who isn't even a Demon Slayer, are you that desperate to die!"
Multiple sashes shot out with extreme speed, cutting through the air with whistling sounds. Mitsuru felt his blood sing—this was the real thing, no holding back, no safety nets.
"Mitsuru-san, danger!"
Tanjiro gasped below, trembling as he tried to stand, but his wounds were too severe. He stumbled and fell again, blood soaking through his uniform.
"Nezuko! Help—"
A sonic boom echoed across the rooftops. Mitsuru's body blurred, Total Concentration Constant amplifying his physical capabilities beyond human limits. The sashes struck empty air where he'd been standing a fraction of a second before.
Daki's eyes widened in shock. She looked down at where Tanjiro had been lying beneath her, now seeing only empty space. Then she stiffly turned her head to find the figure standing some distance behind her, casually holding the red-haired boy covered in wounds.
She hissed. "That speed—"
Mitsuru gently set Tanjiro down, quickly assessing his injuries. The kid was tough—still conscious despite the blood loss. That protagonist-level determination was no joke.
He channeled a surge of his 2 point energy into Tanjiro, helping stabilize the worst of the bleeding. The energy flowing through his own body could apparently be shared, at least partially.
"Mitsuru-san, that's a demon," Tanjiro explained between pained breaths, coughing. "We're Demon Slayers. You need to—cough—you need to run."
"Run?" Mitsuru couldn't help the slight smile. "Not really my style. Besides, you're in no condition to fight."
He finished his quick field treatment and stood, positioning himself between Tanjiro and the demon. He settled into a ready stance, his sword held in a deceptively relaxed grip. Total Concentration Constant was already active, had been since he'd jumped into the district. His perception expanded, his reflexes enhanced beyond normal human limits.
"Focus on recovering. I'll handle the rest."
"But—"
"Trust me."
Mitsuru turned his full attention to Daki, his eyes gradually taking on a dangerous glint. That thrill of facing death, of standing on the edge—it was intoxicating.
"So, let's start this, shall we?"
"Your funeral," Daki snarled.
Three obi sashes exploded toward him like striking vipers.
Fast. Incredibly fast. But he could see them, track their trajectories—
Duck under the first. Deflect the second with his blade. Spin past the third. The tiles where he'd been standing shattered from the impact of missed attacks, fragments raining down to the street below.
"What—"
He closed the gap in three rapid steps, his sword already tracing a silver arc toward her neck. If he could just—
A wall of sashes materialized between them at the last second, absorbing the strike. But the force still sent Daki sliding backward several feet across the rooftop, her eyes widening in surprise.
"You're faster than you look," she admitted, her voice taking on a more dangerous edge. "But speed means nothing if you can't actually hurt me!"
She wasn't wrong. His blade could cut her, could even decapitate her temporarily, but without the sun-infused properties of Nichirin steel, she'd just regenerate. He needed to stall, keep her busy until backup arrived.
But more than that—he needed this. That edge where skill met danger, where death breathed down his neck.
This time, eight sashes came at once from multiple angles, creating a web of attacks that eliminated obvious escape routes.
Instead of retreating, Mitsuru charged forward into the heart of the assault.
His blade moved in continuous flow—cut through the first sash, deflect the second into the path of the third, duck under the fourth while using the fifth as a springboard to launch himself higher. Each movement flowed seamlessly into the next, born from three months of relentless training.
He landed in close range again, his sword already targeting her arms. If he could slow down her control of the sashes—
But Daki was learning fast. She pulled back while simultaneously hardening multiple obi into steel-like shields. His blade struck with enough force to dent metal, but couldn't break through the layered defense.
"You're good," she said, studying him with new interest. "For a human, almost impressive."
Her grin showed teeth just a bit too sharp. "Which will make it so much more satisfying when I tear you apart!"
The assault intensified. Twelve sashes now, moving in perfectly coordinated patterns that seemed to anticipate his movements. Daki was getting serious, her experience beginning to show through.
Mitsuru's mind raced as he defended, his blade creating a protective sphere around himself. She was testing him, learning his patterns with each exchange.
A sash came from his blind spot. Instead of dodging, he grabbed it with his free hand. He yanked hard, pulling Daki off balance. In that split second of vulnerability, his sword flashed out and severed three more sashes before they could retract.
"You little—!"
Rage colored her features now. She'd been playing with him, but he'd actually managed to disrupt her rhythm, damage her attacks.
The temperature of the battle shifted immediately.
Daki's sashes multiplied, grew more vicious. They came from impossible angles, shifted direction mid-flight, coordinated in ways that shouldn't be possible for separate pieces of fabric.
And Mitsuru was loving every second of it.
His pulse thundered in his ears. This was what he'd been missing in his previous life—real challenge, genuine threat. That perfect edge where one mistake meant death, where skill was the only thing between him and oblivion.
But he was accumulating damage too. A shallow cut on his left arm where a sash had gotten too close. A bruise forming on his ribs from when he'd used a crumbling wall as a platform. Nothing serious yet, but the math was clear.
Eventually, he'd make a mistake. Demons didn't get tired. Humans did.
"Some kind of breathing technique?" Daki observed even as she attacked. "Making you stronger than you should be?"
"Something like that," he admitted.
"Won't help you," she said confidently. "I've killed dozens of Demon Slayers. You're still just human. Still breakable."
A sash burst through the roof tiles from directly below without warning. Another came from above at the same instant—perfect pincer attack.
He couldn't dodge both.
His sword met the upper sash while he deliberately took the lower one on his shoulder, letting it wrap around him. The fabric tightened immediately, trying to crush or slice through, but he'd positioned himself so it couldn't get proper leverage.
Then he pulled with all his enhanced strength.
Daki wasn't expecting it—she'd thought she'd trapped him, not the other way around. She stumbled forward, and his blade was already coming around in a devastating horizontal slash aimed directly at her neck.
If this were a Nichirin Blade, the fight would end here.
But it wasn't.
The sword bit deep, cutting halfway through her neck before the obi sash around his shoulder tightened viciously, forcing him to abandon the attack and rip himself free. Blood sprayed from Daki's wound in a dark arc, but even as he watched, the flesh began knitting back together at visible speed.
"That hurt," Daki said, her voice cold and deadly as her regeneration completed. "That actually hurt."
No trace of the wound remained. But her eyes held a new level of malice.
"No more playing around."
Then the atmosphere changed completely.
A presence emerged from the shadows—heavy, oppressive, radiating killing intent so thick it made the air feel viscous and hard to breathe. Tanjiro, despite his severe injuries, made a small involuntary sound of pure terror.
A hunched figure rose from behind Daki like a nightmare made flesh. Emaciated to the point where every bone was clearly visible, yet somehow radiating more danger than his sister had shown. Sickly green hair. Monstrous, twisted face. Blood-red scythes extending from his hands like natural weapons.
Gyutaro.
"My sister," the demon rasped, his voice like grinding metal, "seems to have found someone interesting."
His gaze fixed on Mitsuru with disturbing intensity. "So handsome, while I'm stuck looking like this. How unfair. I'm so jealous, so jealous!"
The kanji in his eyes confirmed what Mitsuru already knew: Upper Moon Six. The real threat.
"Brother!" Daki's voice held both relief and anger. "This human cut me!"
"I saw," her brother replied, his smile all teeth and malice. "Which means he's worth killing personally."
This was bad. Fighting Daki alone until backup was manageable. Both siblings at once? That changed everything.
Then a blur of pink and white crashed into Daki from the side like a cannonball.
Nezuko had arrived, her flying kick sending the female demon tumbling across the rooftop and away from the others. The demon girl immediately pursued with single-minded determination, her protective instincts overriding everything else.
"Nezuko!" Tanjiro called out weakly. "Be careful!"
"How convenient," Gyutaro said, watching his sister and Nezuko disappear over the rooftops in the distance, their battle continuing elsewhere. "Now I can focus on you without distractions."
His scythes began spinning slowly, an almost casual motion that nevertheless promised death.
"Tell me, human—what's your name? I like to know who I'm killing when they're interesting."
"Mitsuru," he replied, rapidly reassessing his situation. Alone against Gyutaro. No Nichirin Blade. Backup en route but ETA unknown.
The thrill that shot through him was almost frightening in its intensity.
"Mitsuru," Gyutaro repeated, tasting the name. "I'll remember it. Now—let's see how long you last!"
He moved.
No warning, no buildup—just pure explosive speed that made Daki's attacks look sluggish by comparison. The distance between them vanished in a fraction of a heartbeat.
Mitsuru's blade came up on pure instinct, meeting Gyutaro's scythe with a clang that echoed across the entire district. The impact drove him backward, his feet tearing furrows in the roof tiles as he fought desperately to maintain his footing.
"You blocked it!" Gyutaro's manic grin widened in genuine delight. "Most humans can't even see my first strike!"
The second scythe came from the opposite angle before Mitsuru could fully recover. Then the first again. Then both together in a scissoring motion aimed at his torso. The demon's attacks were relentless, overwhelming, each strike carrying enough force to shatter bone.
Track the scythes. Predict the angles. Position blade to intercept.
Total Concentration Constant pushed his reflexes to their absolute limit, but even that was barely enough. His blade moved in defensive patterns, intercepting strikes through a combination of enhanced perception and three months of intensive training.
The demon was toying with him, testing his defenses.
"Not bad!" Gyutaro laughed with genuine enjoyment. "You're actually keeping up! But can you handle this—"
His speed doubled without warning.
The scythes became crimson blurs. Slash from above, thrust from the right, reverse cut from below—all within the span of a single second.
Mitsuru's blade moved intercepting each strike through sheer instinct. But he could feel the strain building rapidly. Each impact sent shockwaves through his arms, his muscles heating up from constant exertion.
His sword was accumulating damage too—stress fractures spreading through the blade with each blocked strike.
Gyutaro observed even as he maintained his brutal assault. "Definitely not any standard form I've seen. Your own style? How creative!"
A thrust aimed directly at Mitsuru's heart. He deflected it, but Gyutaro immediately converted the motion into a spin, both scythes coming around horizontally at neck height with lethal precision.
No time to block both.
Mitsuru dropped flat against the rooftop. The scythes passed inches above him, close enough that he felt the displaced air. He rolled immediately, came up slashing at Gyutaro's exposed legs—
The demon simply jumped, inverting his body mid-air with inhuman flexibility to attack downward with both scythes aimed at Mitsuru's skull.
Mitsuru kicked off the rooftop hard, narrowly avoiding the strike that shattered the tiles where he'd been. He landed in a defensive crouch several meters away, quickly reassessing.
His breathing was elevated but still controlled through iron discipline. Several close calls in the last exchange, but no actual hits yet. His sword showed visible stress fractures now, spreading through the blade like spider webs.
Across from him, Gyutaro looked completely unharmed. Not even slightly winded.
"You're good," the demon admitted with what sounded like genuine respect. "Really good. Better than most Demon Slayers I've killed over the years. But here's your problem—"
He gestured to himself casually with one scythe. "I don't get tired. You do. Eventually, you'll slip up. Eventually, I'll cut you. And my poison—" His grin widened grotesquely. "—my poison kills in minutes."
"Noted," Mitsuru said quietly.
War of attrition. The demon had infinite stamina. Mitsuru decidedly did not.
But he didn't need to win. Just survive long enough for—
"Blood Demon Art: Flying Blood Sickles!"
Gyutaro raked his scythes across his own arms without any warning. Blood sprayed out in arcing streams, but instead of falling, it crystallized mid-air into crescent-shaped projectiles that hung suspended like frozen raindrops.
Then they all launched at once.
Dozens of blood sickles moving at supersonic speed, each one coated in lethal poison. They came from every angle simultaneously, filling the air with crimson death that left no obvious escape route.
Can't dodge them all. Can't possibly block them all with a damaged normal sword.
Time seemed to slow as his mind went into overdrive. Total Concentration Constant pushed to its absolute limit, his perception expanding to track every single blood sickle, calculating their trajectories, predicting collision points.
But it still wasn't enough. Even enhanced, he couldn't track them all perfectly. He needed more focus. More precision. More—
_"I made a promise."_
The mantra crystallized in his mind with perfect clarity. Akane's face flashed before his eye. The promise he'd made to always be there, to protect her, to never let her face the world alone.
Repetitive Action—activated.
His concentration sharpened to an absolute razor's edge in an instant. Every detail of the battlefield became hyper-focused with perfect clarity beyond anything he'd experienced before. He could see the individual droplets of blood forming into weapons, track their exact spin patterns, predict their precise paths with mathematical accuracy.
His mind didn't just accelerate—it transcended normal limits entirely.
His body moved.
The sword became a silver blur, intercepting blood sickles with perfect precision. Twist, spin, deflect—each motion flowing seamlessly into the next without a single wasted movement. Sickles shattered against his blade or were redirected into each other with pinpoint accuracy, exploding in sprays of poisonous blood that never came close to touching his skin.
Thirty sickles destroyed in less than three seconds.
"Impossible!" Gyutaro's shock was completely genuine, his eyes wide. "No human should be able to—"
But Mitsuru was already moving, closing the gap while the demon was still off-balance from surprise. His enhanced concentration showed him the opening—a tiny fraction of a second where Gyutaro's guard was lowered, his stance imperfect.
His blade lashed out in a perfect thrust aimed directly at the demon's throat.
Gyutaro twisted desperately at the last possible instant. The sword missed his neck by millimeters but carved a deep, vicious furrow across his shoulder instead. Black blood sprayed out as the demon kicked backward, putting distance between them.
The wound was already healing, flesh knitting back together at visible speed. But for a brief moment, Mitsuru had broken through the demon's defense completely.
"This is great!" Gyutaro's grin turned absolutely manic, his eyes gleaming with bloodlust. "This is amazing! Finally, someone who can actually challenge me! Let me show you—let me show you what an Upper Moon can really do when we stop playing around!"
But before Gyutaro could unleash whatever devastating technique he was preparing, a massive explosion cut through the night air.
Then a voice, loud and flamboyant and unmistakable: "FOUND YOU!"
A figure burst onto the scene with dramatic flair, landing with enough force to crack the remaining intact rooftop tiles in a spiderweb pattern. Tall, powerfully built, distinctive white hair and flashy headband catching moonlight, two Nichirin blades gleaming with lethal promise.
Tengen Uzui had arrived.
Behind him, two more figures dropped down—Zenitsu and Inosuke.
"Well, well," Tengen said, his grin fierce and ready for battle. "Upper Moon Six! This is gonna be flashy!"
His sharp gaze swept across the battlefield rapidly, taking in destroyed rooftops, injured Tanjiro, and Mitsuru standing against an Upper Moon with a visibly cracked blade. "Where's the other one? The sister?"
"Fighting my sister—over there!" Tanjiro called out weakly, pointing toward where distant sounds of violent combat could be heard.
Tengen nodded sharply, immediately making decisions. "Zenitsu, Inosuke—support the demon girl! Take down the sister! Don't let her rejoin her brother no matter what!"
The two younger slayers immediately took off across the rooftops without further argument, heading toward the sounds of Nezuko and Daki's battle.
Tengen turned his full attention to Gyutaro, then briefly to Mitsuru. The Sound Hashira could hear it, could sense it through his enhanced senses: Mitsuru was maintaining Total Concentration Constant even now, even after that intense fight.
"Holding off an Upper Moon alone with just a normal blade?" Tengen said, spinning his Nichirin blades casually. "That's impressive enough that I won't ask too many questions right now. But from here on out, we do this properly."
He took his position beside Mitsuru, facing Gyutaro together as equals. "Stay on your guard—Upper Moons don't go down easy. Trust me, I know."
"Understood," Mitsuru said, finally letting his Repetitive Action state fade away.
The enhanced concentration drained out of him gradually, leaving him with just his Total Concentration Constant baseline. He was exhausted—mentally more than physically, that technique taking a toll he hadn't fully anticipated. But the thrill was still there.
"It seems your luck isn't very good," he said to Gyutaro, meeting Tengen's amused. "Let's move on to the next round!"
Tengen laughed, the sound full of anticipation. "Now that's the spirit! This is gonna be one hell of a flashy fight!"
The real battle was about to begin.