Chapter 10: Are Blades Truly Such Inconvenient Things?
His name was Seishumaru.
In this blockaded mountain range, he wasn't among the strongest. At least four or five other demons here could push him around. But now, those arrogant "top-tiers" had been turned into fertilizer.
Yet, Seishumaru still stood.
He even dared to stand brazenly before members of the Demon Slayer Corps. His confidence stemmed entirely from his unique ability.
[Blood Demon Art: Oxidizing Rust]
This was a supernatural power granted by the progenitor of all demons—Kibutsuji Muzan. It evolved as the demon consumed more humans, and Seishumaru's specific variation allowed him to instantly rust and corrode almost any metal he touched.
It only worked on metal. It did nothing to human flesh or bone.
But for swordsmen who relied entirely on their Nichirin Swords? It was a nightmare. As long as he willed it, any blade that struck him would crumble into useless flakes of rust within a heartbeat.
A swordsman without a Nichirin Sword was no different from a declawed kitten.
"I'll devour all of you and then find a way to escape this mountain," Seishumaru hissed. "Once that Lady sees my power, she'll surely make me one of the Twelve Kizuki! My ability is the natural hard-counter to you sword-swinging brats!"
He lunged forward, forcing Natsuya to shove Seiko back and dodge several swipes.
"So, what you're saying is... you aren't even a Mid-Boss?" Natsuya asked, testing the waters. "And who is 'that Lady'?"
Not even a Mid-Boss?!
Natsuya's words hit a nerve. Seishumaru roared, his frantic clawing becoming even more violent. "You have no right to know her name! Just do what the other swordsmen did and stay still while I eat you!"
The other candidates, seeing Natsuya "struggling," rushed in to provide support. But within seconds, three more Nichirin Swords were reduced to scrap metal. The swordsmen stood frozen, unsure whether to keep attacking or retreat.
"So annoying... you flies!"
Frustrated that he couldn't land a clean hit on Natsuya, Seishumaru turned his attention to the unarmed, regular swordsmen. But just as he moved to strike, a heavy blow slammed into his abdomen.
It hit with enough force to nearly knock the stomach acid out of him.
"You..."
A stunned Seishumaru realized that the boy before him hadn't shown a shred of panic. Not even when his primary weapon was destroyed.
"I asked you a question. Be a good NPC and answer it."
Taking advantage of the demon doubling over in pain, Natsuya transitioned into a fluid knee-strike. It caught the demon squarely on the bridge of its nose. Dark blood sprayed everywhere, coating the demon's own face.
With a cry of agony, Seishumaru's vision blurred. Even for a demon, the nerve endings in the nose and face remained highly sensitive.
Before he could recover, his feet were swept out from under him, and he slammed onto his back.
"Tell me," Natsuya said, standing over the downed demon. "What are the Twelve Kizuki? Are they the upper management? And this rusting ability—is it unique to you, or can the high-level Bosses do it too?"
"..."
Seishumaru stared up at the blurry night sky, his brain failing to process the situation. This is the Final Selection ground, right? This kid isn't even a real Slayer yet... why the hell is he this strong?!
"I'm talking to you."
"I'LL KILL YOU!" Seishumaru scrambled to get up, snapping his jaws at Natsuya's throat.
But before he could even get his torso off the ground, he was effortlessly floored again.
Even as a demon, Seishumaru still followed the mechanics of a humanoid body. A stand-up motion starts with the core, supported by the neck and arms, and finalized by the kinetic chain of the hips and lower limbs.
For Natsuya, it was simple: Just break the chain.
He stomped on the demon's knee, then leaned his weight forward, slamming his right palm into the demon's forehead with the force of his entire body.
CRACK!
Seishumaru was hammered back down even faster than he had tried to rise. The back of his skull bounced off the jagged stones on the ground. The impact was so severe it nearly knocked him unconscious.
The surrounding swordsmen felt a chill run down their own spines just watching. This guy is... disturbingly experienced at this.
For Natsuya, this was muscle memory. It was just an "Okizeme" (pressing an opponent as they get up)—except easier than any fighting game he'd ever played. After all, in this world, there was no such thing as "I-frames" or "Wake-up Super Armor."
"If you talk, I might consider letting you go," Natsuya lied.
Shame and rage finally boiled over. Seishumaru screamed, "How the hell should I know stuff like that?!"
Natsuya frowned. "What about your Boss? You were just bragging about wanting her approval. Don't tell me you don't know who she is."
The demon's expression froze. As if remembering something truly terrifying, it shivered involuntarily before doubling down on its bravado.
"You brat... even if you kill me, I won't say a word! Besides, you don't even have a sword! How are you going to kill me?! Hahaha!"
Natsuya let out a small, disappointed sigh. I guess I'd need a 'Torture' skill or a special quest item to get intel out of these mobs.
Whatever. There will be plenty of other demons later. The high-ranking Corps members probably already have this info anyway. Better to just push the main quest.
Natsuya's next punch carried his full weight. With the strength boost from his Breathing Style, a single blow turned the demon's face into a bloody pulp.
Then came another. And another.
A relentless rain of fists fell like a thunderstorm. Seishumaru tried to fight back, tried to crawl away, but every attempt was snuffed out by Natsuya's overwhelming "Ground and Pound."
To the observers, it looked like Natsuya was using the demon as a target dummy.
This was a simple matter of physics. Aside from the tricky Blood Demon Art, the demon's raw strength was inferior to Natsuya's when he was using Wind Breathing. And technically? The demon was an amateur. It didn't know the first thing about grappling or Brazilian Jiu-Jitsu.
It's a victory for martial arts, Natsuya thought.
Still, the demon's mouth remained functional. "Is that... all you've got?! You're strong? Big deal! I'm an immortal demon! You can hit me all night, but you can't kill me without a blade! It's hours until sunrise—you think you can keep this up?! Just give up and let me eat you. I'll be merciful and snap your neck quickly, hahaha—"
Natsuya's fists slowed to a halt. "You actually have a point."
The surrounding swordsmen gasped. One of them shouted, "Don't listen to him! We'll help you hold him down until dawn! We can win this!"
Seiko, however, stepped in front of them, blocking their path. "Natsuya-kun knows what he's doing," she said firmly.
"Seiko's right. She's the smart one," Natsuya muttered.
CRACK! CRACK! CRACK!
With brutal efficiency, Natsuya shattered the demon's limbs. He stood up, picked up the jagged half of his broken Nichirin Sword, and walked back to the demon's head.
"I assume you've eaten quite a lot of people," Natsuya said. "Your nameplate is a very bright shade of red."
"S-Stop... that hurts..." Seishumaru hissed through the pain. "The sword? Are you stupid? You think that piece of junk can hurt me now?"
Natsuya's face remained expressionless. "Did you forget? I already cut your arm off once."
"Huh?"
The blade broke, yes. But I successfully severed the limb before it snapped. That means the rust doesn't happen instantly—it takes a fraction of a second.
"As long as the slash is faster than the oxidation... it works."
Natsuya gave the broken blade a test flick, adjusting to the balance of the shortened steel.
"Besides... do you really think a broken blade makes me less dangerous?"
[Total Concentration Breathing]
In that instant, Natsuya's Power Level began to skyrocket. His Body stat surged from 26 to a staggering 52.
"Wind Breathing, Fifth Form: Cold Autumn Mountain Wind!"
A line of frost-white energy tore through the air. The chill of late autumn seemed to permeate the mountain for a single heartbeat.
The downward strike was so fast it bypassed the rust entirely, shredding Seishumaru's neck and skull into nothingness.
Natsuya landed softly and performed a "sheathing" motion with the hilt.
"Are blades truly such inconvenient things?"
As he spoke, the remaining half of the Nichirin Sword finally crumbled into gray ash.
[Proficiency: 419/2000 (+156 XP)]
High XP payout, but it's a real durability sink, Natsuya noted.
He looked over at the group of stunned examinees and gave them a casual wave.
"Hey. Someone give me a sword."
"Shota-taro? Don't just stand there."
Goda Shota was still in a trance, whispering to himself, "Was that... the gale that shreds all evil?"
Natsuya realized he'd forgotten to turn the [Breathing VFX] back on. Wait, if it looked that cool to them without the effects, maybe I should keep them off? No, let's keep them on for the 'immersion'.
Seiko walked over to one of the fallen swordsmen and retrieved a spare Nichirin Sword.
"Natsuya-kun... please, use this. Don't... don't be offended that it's a hand-me-down."
Natsuya gave the sword a few test swings and sheathed it. Offended? Why would I be offended by free loot?
He looked at the candidates who were slowly regaining their senses. "The mountain is probably mostly cleared out by now. Follow me. Help me find any stragglers I might have missed."
"We aren't leaving a single mob behind. It would be a waste of XP."
The examinees nodded frantically. One girl shivered, looking at Natsuya with wide eyes. This guy... his bloodlust is terrifying.
"Any problems? Speak up now."
"N-No... sir!"
"Is... is it okay for us to group up like this? Does it count as cheating?"
"I think... I think it's fine..."
The group hesitated for a second. Natsuya raised his voice slightly. "Is there a problem?"
The entire group flinched simultaneously. They looked at the devastating crater he'd left in the ground and remembered the chilling, expressionless face he wore while pummeling a demon.
He must be one of those 'Dark Vengeance' swordsmen... someone whose family was slaughtered and has turned into a combat demon... if we say no, will he cut us down too?
"WE ARE IN YOUR CARE, SENSEI!"
The entire group suddenly bowed in a perfect 90-degree angle.
Whoa. Such energy... wait, do I look like a villain to them?
Natsuya turned to Seiko, confused.
The girl was clutching her stomach, her shoulders shaking as she tried to stifle a laugh. Her face was turning beet-red from the effort.