---Third POV---
Watching Sukuna getting swallowed by the sea of sand, Ryouma muttered to himself, "I really can't tell whether the Sage of Six Paths actually couldn't kill monsters like you, or if there's some other reason. But you're not that strong."
Even as he spoke, his hands moved without pause, rapidly forming seals. Black sealing slithered toward the demon as he was engulfed by the flowing sand.
But just as things seemed settled, the unexpected happened.
Every villain boss had to have their mandatory second-phase transformation, and Sukuna's had arrived.
Beneath the shifting sands, the demon's skin suddenly split open with tearing sounds. Black blood seeped out, forming twisted tattoos across his bare torso. The markings glowed and spread across his muscles like infection.
He pressed his palms together before his chest, and in an instant, a violent aura burst outward, scattering the sand.
"In this form, I won't show mercy anymore. Hope you can last a little longer, don't go dying before I capture you alive."
His legs moved like pistons, striding across the sand as if it were solid ground. In less than a second, he crossed a hundred meters, swinging a slash directly at Ryouma's head.
Just as the blade was about to connect, space twisted slightly, Ryouma's figure vanished.
The demon's strike hit nothing, sending up a massive plume of dust and sand.
Ryouma had already placed countless Flying Thunder God marks throughout the sea of sand. Unless Sukuna could close the distance faster than his Rikugan could react, within this battlefield, he was untouchable.
But he wasn't content to just play keep-away.
As he materialized at a new location, invisible energy coated his arms. Haki wrapped around him like a second skin, hardening his limbs. He wanted to sharpen both his Armament and Observation Haki, and Sukuna was the perfect training partner.
"Let's see how that legendary martial skill holds up," he said, launching himself forward.
Sukuna brought up both bone blades to block. Ryouma's fist crashed into them, but the demon held firm. The bastard was strong.
Before Sukuna could counter, Ryouma grabbed one of the crossed blades with his left hand, and drove his right elbow down toward the demon's face.
Sukuna twisted away, but not fast enough. The elbow clipped his jaw, snapping one head to the side.
The demon snarled and ripped his blade free, then swung with his other three arms simultaneously, a bone blade from the right, a backhand from above, and a grab from the left.
Ryouma ducked the blade, caught the grabbing hand at the wrist, but the backhand caught him across the temple. Armament Haki absorbed most of it, but the impact still rattled his skull and he stumbled.
Sukuna pressed forward, all four arms working together. Ryouma jumped back, slipping between blows that could've taken his head off. A blade passed near his ear, another scraped against his ribs without cutting through.
He grabbed Sukuna's left wrist as it thrust a blade at his gut, used the grip to swing himself around behind the demon's arm. Now he had leverage. He drove his knee up into the elbow joint.
Something popped. Sukuna roared and spun, trying to shake him off, but Ryouma held on like a tick. He wrapped his arm around the demon's throat from behind and squeezed.
The other three arms came up, trying to claw him off. Ryouma pressed his face against Sukuna's back to avoid the worst of it, but claws raked across his shoulder.
Sukuna slammed backward into a rocky outcrop, trying to crush him. The demon did it again, harder. Rock fragments showered down.
On the third slam, Ryouma let go and rolled away.
They circled each other.
"Not bad for a human," Sukuna admitted, flexing his good arms. "But you're bleeding."
"So are you."
The demon grinned with both mouths. "I heal faster."
He was probably right. Ryouma could already see the swelling in his jaw going down.
Sukuna feinted left, then came in low and fast from the right. Ryouma saw through the fake and stepped into the real attack, accepting a glancing blow to his hip to get inside the demon's guard.
He hammered short punches into Sukuna's ribs. The demon's hide was tough as steel, but force was force. He felt something give under his knuckles.
Sukuna grabbed him in a bear hug, lifting him off his feet. Four arms squeezed, trying to pop his ribs.
Instead of fighting the hold, Ryouma relaxed for just a second, then exploded upward. His forehead cracked into Sukuna's chin, snapping both heads back. The demon's grip loosened.
Ryouma slipped down and out, then swept Sukuna's legs. The demon went down hard, four arms flailing for balance.
But he recovered fast, rolling backward and coming up in a crouch.
"Getting tired already?" Sukuna taunted. "This is why humans are weak."
Ryouma spat blood and wiped his mouth with the back of his hand. The demon hit like a truck and moved like lightning. Still, his body was toughening with every blow. The pain was worth it. Time for a tactical retreat.
That's when the real show began.
BOOM! BOOM!
The earth trembled violently, as if some colossal beast was breaking free from the depths. The air grew thick with the stench of rot and blood that made even hardened ninjas gag.
Ryouma instantly activated his Rikugan, and what he saw made him frown deeply.
From every direction, countless monsters surged forward. Creatures of all shapes came rushing, spider-like horrors with too many legs and eyes, giants made of bone and sinew, and bizarre beings that defied description.
It was like the land had transformed into a Night Parade of 100 Demons.
Sensing the aura of his kind, Sukuna's mouth stretched into a grin. "It's not too late to accept my deal. Or are you planning to use that space-time ability of yours to flee like a coward?"
"Flee?" Ryouma gave a chuckle. "Why would I need to flee?"
He had already made his decision. He knew that only the Land of Whirlpools could produce black moonstone, and he'd need to return here for mining in the future. Since these monsters had chosen to come to him, he might as well clear the board today and remove all obstacles to his future plans.
---
Hidden in the shadows of a distant mountain peak, Ashina, under Black Zetsu's control, was watching the battle.
"To think even the power of these monsters could be reflected back... This ability goes beyond the scope of chakra."
Through Black Zetsu's eyes, Ryouma's reflecting power was no longer something that could be called normal jutsu. The scope of its application was at least on par with the secret techniques of the Ōtsutsuki clan.
Just who exactly are you?
He began to seriously suspect that perhaps the one before him was actually an Ōtsutsuki in disguise. The very thought sent chills through him, yet it also made sense. Otherwise, how could one explain why a mere descendant born from scattered chakra fragments could rise up and overthrow Indra's reincarnation?
But if that were true, then this bastard's disguise was flawless. Or perhaps he truly was a native, just one who had been branded with a Kāma seal.
The current intelligence was insufficient; everything remained speculation. He continued to silently observe the battle unfolding below Mount Sukuna, waiting to see if Ryouma would be forced to enter that golden form he'd glimpsed in the Land of Grass.
---
At the foot of Mount Sukuna, the air had become a battlefield.
Ryouma played cat and mouse with his foes, once again invoking Flying Thunder God to dodge Sukuna's vicious charge.
But this time, the demon wasn't the only one attacking.
From above, a swarm of half-human-sized insects came down, blotting out the sky.
"Time to turn up the heat," he muttered.
The air around him suddenly grew scorching hot as he raised one hand above his head. Massive amounts of chakra gathered in his palm.
In the blink of an eye, a colossal Grand Flame Rasengan had formed.
The next moment, searing flames erupted. The massive fireball split apart into countless smaller flame bullets, raining down. The dense barrage engulfed the swarming horde, turning the sky into a sea of fire.
Wherever the flames spread, the creatures shrieked in agony before crumbling into ash.
Within moments, the entire swarm had been annihilated, leaving only the stench of charred chitin and rising heat waves.
Lowering his arm, he drew his blade with a reverse grip. Blaze chakra surged from his palm, winding up the steel and extending its edge several times over as flames danced along its length.
With a swing, his Full Counter domain expanded outward, but only briefly, just long enough to catch and reflect an orange-red beam that had been launched from behind him.
The reflected attack struck into a massive one-eyed volcanic-headed monster, catching it completely off guard. Half of its body was obliterated before it tumbled helplessly into the sea of sand below, ichor spraying everywhere.
"Ryouma, this one's different from the rest. It needs to be sealed," came Kurama's timely reminder.
"Leave it to me!" Shukaku seized the moment. Black sealing writhed forth, instantly binding the wounded volcanic monster deep in the sand sea, rendering it completely immobile.
"Nice work!" Ryouma praised without hesitation. His perception went into overdrive as he combined Observation Haki, Rikugan, and the Breath of All Things. He locked onto critical points all across the creature's form.
He gripped his blade with both hands and unleashed two sweeping arcs. The blazing strikes tore through the air before plunging into the sand sea, precisely severing the critical points.
The volcanic monster let out a shrill scream. It couldn't comprehend why, as a demon with supposed immortality, its life had been ended by such a straightforward attack.
With that unanswered doubt lingering in what passed for its mind, its body slowly dissolved into a plume of black smoke, scattering into the wind.
Witnessing this scene, the surrounding powerful monsters, those with self-awareness, abruptly halted their advance. Hesitation and fear flashed across their features.
They had all thought, "At worst, I'll just be sealed again," believing that even if defeated, they could still cling to existence as they had in the past. But the fate of that volcanic demon made them realize something that chilled them, this time, death was real.
In terms of resilience and immortality, some among them were even weaker than the creature that had just perished.
At once, a wave of terror doused their battle fury like ice water. Their expressions changed instantly, they scrambled to flee in panic, tripping over each other in their desperation to escape from this terrifying human.
---
From his hidden vantage point, Black Zetsu felt his nonexistent scalp prickle.
His eyes were locked on the battlefield as he pondered: "What kind of ability is this?"
When Ryouma had slain the lesser monsters earlier, he had paid little attention, assuming it was merely the power of Blaze Release techniques. After all, fire was indeed effective against low-tier creatures.
But now, facing this powerful monster that had been sealed during Kaguya's era, Ryouma's display finally revealed something deeper.
It was clear, Aotsuki Ryouma possessed some ability that could bypass the immortal nature of these ancient demons. Blaze Release alone could never have killed that volcanic creature.
---
At the foot of Mount Sukuna, Ryouma swept his gaze over the fleeing monsters.
"Running? A bit too late."
Bang! Bang! Bang! Bang!
Four bursts of smoke erupted as Ryouma formed seals with one hand and created four shadow clones. The clones, needed no words, they instantly understood his intent and teleported using Flying Thunder God, positioning themselves at the four corners of the sand sea's perimeter.
"Four Red Yang Formation!"
Four scarlet beams of light shot skyward, connecting in pairs to form a massive four-sided barrier that enclosed the entire battlefield.
Among the scattering monsters, Sukuna was naturally the swiftest. And naturally, he became the first unlucky bastard to slam face-first into the Four Red Yang Formation.
With a roar, his arm muscles bulged. The two bone blades in his hands came down.
"BREAK!"
Two blinding white cross-shaped arcs of light tore through the air, striking the crimson barrier.
The wall of the formation warped violently under the sheer power, and a smug grin spread across both of Sukuna's faces.
But in the next instant, everything reversed.
The crimson barrier suddenly rebounded with great force, unleashing a shockwave. It easily shattered Sukuna's stance and blasted the demon away.
BOOM! BOOM! BOOM!
Sukuna's body crashed through several mountain peaks in succession, unable to control his flight under the recoil.
Finally, he slammed into the main peak of Mount Sukuna itself, carving out a crater the size of a building before coming to a stop.
"Cough! Cough!"
He struggled to climb from the pit, spewing several mouthfuls of black blood. His regeneration was working overtime just to keep him conscious.
"What kind of ridiculous barrier is this?" he wheezed, feeling like his entire body was about to shatter into pieces.
He had been secretly celebrating while escaping earlier, fortunate that his speed in the second phase was fast enough. With the explosive momentum, he had scattered the surrounding sand before the sealing techniques could bind him. Otherwise, he would have ended up just like that volcanic demon.
But now it seemed that Ryouma had no intention of letting any of them escape. This barrier was tougher than the hide of the legendary beasts that had once been sealed alongside him.
Just then a voice drifted down from above.
"Using bone blades to hack at the Four Red Yang Formation? I really should give you points for creativity."
Sukuna's antics reminded Ryouma of Kushimaru, whom he'd killed on the Kiri battlefield. That idiot had done exactly the same thing, charged at the barrier formation as if it were made of paper, only to be crushed by the rebound. Some lessons never got learned.
Sukuna's four eyes glared up at the sealing spreading rapidly across his body. He spat out, "Must you really hunt us to extinction? We could at least—"
Shink!
The whistle of a blade cutting through air silenced his words forever.
Ryouma had no patience for a monster's final words.
"AAAARRGH!"
The demon let out a shrill wail as his body rapidly collapsed, dissolving into a pool of black filth before vanishing.
"ROAAAAR!"
There was no moment of mourning for Sukuna's death. What followed was a surge of desperation from the monsters who had witnessed his execution.
They knew now that escape was impossible. Trapped within the barrier, with death as the only alternative to victory, they could only swallow their terror and prepare to fight this human monster.
The earlier plan, to capture this man with space-time powers and force him to ferry them off the island, was nothing but ash and broken dreams now.
Now, their only goal was survival. And maybe, if they worked together, they could overwhelm even this terrifying human.
Reality proved that under immense external threat, even selfish, self-serving monsters could unite as one. After all, unlike the Sage of Six Paths who had shown mercy in the past, this bastard actually killed demons when he caught them.
No negotiations. Just death.
Some of the less intelligent creatures let out growls.
Thump... Thump...
Ryouma strode forward, stepping onto the peak of Mount Sukuna. From there he looked down at the horde of monsters below.
Fortunately, the vast majority were only low-tier demons that had been sealed by the Uzumaki clan in later generations. They could be slain without requiring his most advanced techniques, just precision, power, and the will to see the job through to its bloody conclusion.
Otherwise, if he had to strike down each critical point individually, it would waste far too much time. And he had moonstone to mine once this pest control was finished.