"So, you're the one Muzan-sama handpicked for execution. You think you're worthy of a duel with him? You're nothing but a brat!"
The newly promoted Lower Rank Six, Enmu , glared down at Goku from a high beam, his bifurcated tongue—slick with rows of jagged barbs—licking his lips in anticipation. Since Rui's death, the hierarchy had shifted; the former Lower Six had moved up, and this wretch had been "blessed" with Muzan's blood to fill the vacancy.
But he wasn't satisfied with the dregs of power. He craved the status of the Upper Moons. Muzan had promised a literal ocean of blood to whoever brought him the head of the boy with the strange powers.
Enmu knew better than to charge headlong into a boy who had vaporized Rui, especially with nine Hashira standing behind him like a wall of living steel. Instead, he relied on his specialty. As he spoke, he surreptitiously activated his Blood Demon Art: Incantation of the Bewildering Voice.
The technique worked through verbal provocation, weaving a hypnotic frequency into his insults that stripped victims of their reason, forcing them into a mindless, suicidal rage. If the boy succumbed, he would charge blindly into the demon horde, leaving himself wide open for a finishing blow.
"If you want to see Muzan-sama, you'll have to crawl through the corpses of every demon here! But looking at you... I doubt you could even scratch a single scale off my skin!"
"So, I have to kill all of you before Muzan will fight me? I get it now," Goku said, blinking slowly.
He didn't look angry. He looked focused.
Without hesitation, Goku widened his stance and began to draw a deep, resonant breath. This wasn't just his usual preparation; he began to incorporate the Wind Breathing techniques he had just learned from Sanemi. By forcing massive amounts of oxygen into his bloodstream, he ignited his internal furnace, allowing his ki to surge far beyond its normal limits. The pressure in the air began to hum.
"What is that...?"
The Upper Moons, who had been watching with detached amusement, suddenly felt their instincts screaming. A blinding, crystalline blue light began to coalesce between Goku's cupped palms, pulsating with a rhythmic, heartbeat-like thrum.
"KAMEHAMEHA!"
Goku thrust his hands forward. A titanic pillar of cerulean energy erupted, wider than a temple gate and hot as a collapsing star.
"GET OUT OF THE WAY!"
The scream came from the Upper Moons, whose sensory organs were being overwhelmed by the sheer density of the incoming attack. They didn't just see the light; they felt the conceptual threat of *erasure*.
The Upper Ranks—Akaza, Doma, and Kokushibo—blurred out of existence, using their god-like reflexes to leap into the spatial folds of the castle. But the Lower Ranks and the rank-and-file demons were not so fortunate. They tried to deploy their own Blood Demon Arts, thinking that a thousand-fold barrier of bone, ice, and shadow could withstand a physical blow.
Some even scoffed, relying on their immortality. They figured that as long as their necks weren't touched by Nichirin steel, they could regenerate from a single cell.
They were catastrophically wrong.
The Kamehameha didn't "cut" or "crush." It disintegrated. The vanguard of a thousand demons didn't even have time to scream before they were flash-vaporized. Their Blood Demon Arts shattered like glass under a tidal wave. Their bodies didn't turn into gore; they turned into light and ash. Every cell, every drop of demon blood, was scorched out of existence.
The beam roared through the wooden architecture, punching through hundreds of rooms and then continuing upward. It tore through a thousand meters of solid bedrock and mountain soil, erupting out of the earth's crust like a volcanic vent and piercing the evening sky.
When the light finally faded, the Infinity Castle was silent.
A massive, glowing tunnel now led straight to the surface world. Of the Twelve Kizuki, only the six Upper Moons remained, scattered across the distant edges of the wreckage, their faces pale and their clothes singed.
The Lower Ranks? Gone. Erased.
The army of a thousand lesser demons? Reduced to a shivering remnant of barely a hundred stragglers who had been standing at the absolute periphery. They were trembling so violently they could barely hold their weapons.
Even Muzan, sensing the devastation through his shared hive-mind, felt a cold, paralyzing dread he hadn't known since the Sengoku era.
"What... what kind of monster is he?" Akaza whispered, his golden eyes wide with a mix of terror and obsessive lust for such power.
Behind Goku, the Demon Slayers were frozen. Many had their swords half-drawn, their battle cries dying in their throats. They had seen Goku use this move before, but never like this. This wasn't a technique; it was a force of nature.
Nine Hashira looked at the boy's back, realizing that in their earlier "sparring," Goku hadn't even been playing. He had been holding back a literal sun.
"The speed of the Kamehameha is still a bit slow," Goku muttered, shaking out his hands. "I didn't get them all."
He wasn't satisfied. He knew the heavy hitters had escaped. He also knew that while his other techniques like the Dodonpa were faster, they didn't have the "area denial" necessary to ensure a demon couldn't regenerate. He had used the Kamehameha specifically to clear the "trash" so the weaker slayers wouldn't be swarmed in a chaotic melee.
"Moon Breathing, Sixteenth Form: Moonbow - Half Moon!"
High above, Upper Rank One, Kokushibo, struck. He had realized that they could not allow this boy to fire a second shot. He unsheathed his grotesque, eye-covered blade and descended like a falling star, unleashing a chaotic rain of crescent-shaped blades that sliced through the very air.
"Blood Demon Art: Crystalline Ice - Bodhisattva Lotus!" Upper Rank Two, Doma, followed suit. A gargantuan statue of ice materialized behind him, exhaling a freezing mist of sharp ice crystals designed to shred a human's lungs from the inside out.
"Technique Development: Blue Silver Chaotic Glow!*" Akaza roared, diving in from the flank. He unleashed a hundred vacuum-shell punches in a single second, each one aimed at a vital organ.
The three strongest Upper Moons were no longer testing him. They were moving in for a synchronized, total-annihilation strike.