Clang—
Amid the sound of clashing metal, Gusion was sent flying. But this wasn't a sign of panic—instead, he'd deliberately relaxed his body, letting himself be struck away to dissipate the force.
Kokushibo's Moon Breathing was indeed formidable. His Third Form: Loathsome Moon, Chains was a wide, double-slash technique—its speed and power honed over countless years. Even Gusion barely had time to adjust his stance in that instant.
So, all he could do was use his Mazuko Sword to barely protect his vitals. Without that—and even with Armament Haki wrapping his body—Kokushibo's blade would have cut him in half.
After a brief exchange, Gusion understood: though Kokushibo was only Upper Moon One and technically Muzan's subordinate, in direct combat strength, he might not be any weaker than Muzan—in fact, possibly even stronger.
Previously, when he slashed at Muzan, he'd glanced at Muzan's stats:
[Kibutsuji Muzan]
Constitution: 46
Strength: 41
Agility: 42
Spirit: 38
Charm: 10
[]
Looking at the stats alone, Muzan wasn't much stronger than Kokushibo. Muzan was tankier, with the resilience of a Demon King—he wouldn't die even if decapitated, and his regeneration far surpassed other demons'.
But all Muzan's abilities seemed focused on survival; his actual attack power was average. And because he always relied on his subordinates to fight, despite a millennium of life, he had little true combat skill.
Thus, Muzan was the kind of waste who had high stats but posed little real threat in battle. In Gusion's view, Kokushibo was more dangerous.
When Kokushibo used Moon Breathing, his stats even increased a bit, making his attacks lethal—getting hit was fatal or crippling.
After being knocked back, Gusion crashed into a door, then used it as a springboard, launching himself at Seifu above.
His strategy was simple: in the chaos, take out the opposing support-type first, to avoid being ambushed later. Plus, Seifu was a powerful scout—who knew what tricks he had? Killing him first was safest.
Seifu watched as Gusion charged with blinding speed. No matter how many invisible threads he wove, he couldn't stop Gusion—he found it unbelievable.
His threads were supposed to be invisible; how did Gusion always spot his setups, dodging at the last moment before getting cut?
If his threads couldn't bypass Gusion's senses, then they were just tough, sharp lines—he had no advantage over the top Upper Moons, and was even weaker than the original Upper Moon Four in direct combat.
He tried to leap away across platforms to evade, but Gusion was too fast—moving like living lightning, thunderclaps echoing as he zipped through.
It was a terrifying fact: Gusion's speed had surpassed the speed of sound. That wasn't something a person with 40 points in Agility should be able to do.
"Damn it, what footwork are you using!?"
Seifu was panicking now. He intentionally fled toward clusters of demons, but none of them—even an Upper Moon Eight—could slow Gusion down. They were all instantly slain.
In his mind, he was supposed to be a hero in this world—how could he get killed by a villain like Gusion!?
Seeing Gusion close in, Seifu could only shout, "Big Bro, help me!"
Kokushibo obliged, or maybe just happened to arrive by shortcut, slashing at Gusion. Instantly, moonlight flooded the platform.
Because Gusion was so fast, Kokushibo couldn't predict his movement, so he unleashed a barrage of vertical crescent slashes, covering a 180-degree arc—a technique that could annihilate everything nearby.
Moon Breathing, Land Form: Eternal Night, Solitary Moon—Infinite.
But even as Kokushibo unleashed this move, the high-pitched sound of clashing blades echoed across the platform—blinding sparks flickering in rapid succession. Gusion, in a flash, blocked every slash, his speed barely dropping.
The moment the metallic clangs fell silent, his chant ended. He raised his left hand, pointing at the fleeing Seifu in the distance:
"Bakudō #61: Six Rods Prison of Light!"
Suddenly, six beams of light appeared, pinning Seifu from all directions and locking him in place.
Kokushibo was surprised by Gusion's move, and in that moment of confusion, Gusion broke through his technique's blockade. The speed of his dash caused sonic booms as he rushed to finish off Seifu.
No matter how Seifu struggled, he couldn't break free from the Six Rods Light Prison. Realizing his fate, his face twisted in desperate anger:
"F*ck you! Are you a Shinigami!?"
He finally understood why the demons Gusion killed didn't leave corpses—because Gusion wasn't using a Nichirin Blade or poison. He was wielding a Zanpakutō!
If a demon's head was cut off by Gusion, it was like their soul itself was severed—utter annihilation.
Gusion didn't reply. As he passed Seifu, he sliced off his head and, with a sweep of his left hand, stowed the Dead Man's Chest into his inventory.
Infinity Castle was too chaotic—he worried he'd lose track of the loot if he waited until after the fight.
"Are you human or demon!?"
Muzan, watching from afar, was terrified at the sight of Gusion using this strange "Blood Demon Art." It frightened him even more than Gusion's raw power.
He began to doubt himself: Was he truly the only Demon King?
Could that doctor from a thousand years ago have perfected a formula to create demons who feared neither sunlight nor needed to eat humans?
It seemed possible. Gusion not only had a body far stronger than any demon but could also use powerful Blood Demon Arts—and didn't fear sunlight.
After his fear, Muzan felt a surge of excitement. Wasn't Gusion the perfect creature he'd been searching for—one immune to sunlight?
If he could devour Gusion, wouldn't he become the perfect being himself?
Boom—
But an explosion below snapped him back to reality. Kokushibo, after clashing with Gusion, was sent flying, smashing through several doors before stopping.
Meanwhile, Akaza—his wounds just healed—was even worse off, his head knocked off by a single punch from Gusion.
If Kokushibo hadn't intervened, Akaza would have been finished off for good.
Muzan looked at the brutal battlefield, torn inside. He realized Gusion was as tough as Yoriichi from centuries past. If he joined the fray, he might not win and could even put himself in danger.
After much inner struggle, Muzan made a decision: he'd pin his hopes on the intel gathered by his new demons.
According to the now-dead Upper Moon Four and Upper Moon Eight, a girl named Nezuko had overcome sunlight. If he could devour her, perhaps he could gain a sunlight antibody and become the immortal perfect being.
Right now, with Gusion trapped in Infinity Castle, he just needed to have his subordinates stall Gusion while he went to the Demon Slayer Corps' headquarters to wipe out those annoying pests.
He guessed Nezuko was likely under heavy protection at headquarters—just fifty kilometers from where Infinity Castle had ensnared Gusion. That would be the easier target.
With this in mind, Muzan smiled:
"Kokushibo, I'll leave things here to you. I'm off to make myself more perfect. Afterward, I'll help you overcome sunlight, too."
As a boss, he had to motivate his best demon. He could ignore the other Upper Moons, but Kokushibo's power was crucial—he needed him fully committed to blocking Gusion.
Of course, Muzan didn't actually care about Kokushibo's fate. As long as he delayed Gusion, Muzan could absorb Nezuko—and Kokushibo would be useless.
After becoming stronger, maybe he'd avenge Kokushibo by killing Gusion, or maybe he wouldn't bother—perhaps, as the ultimate being, he'd just find a peaceful place for eternal life.
"Don't worry, my lord. I will kill him myself."
Kokushibo stepped from the rubble. Though he'd been knocked back by Gusion, he was unharmed.
At their level, unless decapitated, even severed limbs could regenerate in an instant—so he still saw himself holding the advantage.
After all, Gusion clearly used a secret technique similar to the Demon Marks to boost his power—a method that burned stamina. In a war of attrition, Kokushibo was sure he'd win.
Plus, with so many demons inside Infinity Castle, even if they couldn't hurt Gusion, they'd wear him down.
In fact, after their last exchange, Gusion didn't pursue Kokushibo—he went after the other demons, cutting through them like wheat.
"Nakime."
Muzan called out, asking Nakime to open a door. With precise positioning, he stepped out and arrived at the Demon Slayer Corps' headquarters.
Seeing Muzan leave Infinity Castle, the explorers inside were dumbfounded—then erupted in curses.
"Damn you, Muzan, you idiot boss, you—****"
"Running away now? Are you crazy!?"
"Idiot Muzan, you could've gone after Nezuko anytime—why now?"
"F*cking coward, Muzan, can't you just fight with Kokushibo? What's wrong with a team fight!?"
"We're doomed. Gusion isn't even human—Kokushibo can't stop him, and now that idiot Muzan's run off, aren't we just waiting to die?"
The explorers gave up all hope, cursing Muzan for dooming their side.
They'd already deduced from Gusion's past exploits that he was a terrifying powerhouse—skilled at battle, not inferior to Kokushibo.
Now, seeing him in action, they realized he didn't just match Kokushibo—he surpassed him.
Gusion's stats were also high; Doma and Seifu had barely lasted before being killed. At this rate, Kokushibo and Akaza couldn't stop him—defeat was only a matter of time.
In this situation, if the super-tanky Muzan fought, they might have a real chance to kill Gusion.
But the Demon King wanted to run away now?
"We're ready to fight to the death—why does the boss surrender first?"
The explorers fell into deep despair, realizing their leader—though powerful—was a coward, the most idiotic of idiotic bosses.
After the anger and hopelessness, the remaining explorers turned their despair into motivation and decided to fight for their lives.