Thirty minutes earlier, deep beneath the desolate, wind-swept expanse of the Mountains' Graveyard.
The subterranean cavern was engulfed in suffocating darkness. The silence of the tomb was broken only by the steady, rhythmic dripping of water from the ceiling.
From the solid bedrock of the cavern wall, a dark, viscous shape detached itself. Black Zetsu slid across the cold stone floor, moving like spilled ink, completely devoid of any detectable chakra signature. The ancient entity crept toward the center of the room, stopping just at the edge of the freshly sealed earthen grave.
It stared at the heavy granite slab bearing Madara Uchiha's name.
Black Zetsu did not act immediately. The entity possessed a vast, unparalleled intellect honed over centuries of manipulating reincarnations and orchestrating wars. It recognized the anomaly for what he was: a ruthlessly thorough executioner.
He used a standard earth jutsu to seal the grave, Black Zetsu analyzed, his yellow eye narrowing in the dark. It can be broken easily. Too easily. A man who destroys an entire cavern of clones and obliterates the Susanoo from within does not leave the ultimate prize secured by a simple layer of dirt.
Black Zetsu was intensely cautious. He suspected a hidden layer to the burial, a latent seal or a dormant trap laid within the stone itself. The risk of triggering it personally was too great. Kaguya's revival depended entirely on his survival and the recovery of the Rinnegan. He needed a proxy.
"What a mess," a distinctly different, higher-pitched voice echoed through the cavern.
Black Zetsu turned. Emerging from the solid rock near the cavern entrance was a unique White Zetsu clone. Its body was encased in a strange, swirling, mask-like carapace that covered its entire head, leaving only a single eye hole.
It was Tobi, the eccentric, mutated offshoot of the clone army.
"I leave to scout the northern perimeter, and I come back to find the entire nursery incinerated!" Tobi complained, his tone entirely out of place in the grim, bloodstained cavern. "Everyone is gone! Did Madara have a bad day?"
"Madara is dead," Black Zetsu stated coldly, his raspy voice cutting through the eccentric clone's rambling.
Tobi paused, tilting his swirled head. "Dead? Actually dead this time? Or just pretending again?"
"He was executed by the blonde shinobi," Black Zetsu explained, his yellow eye fixed on the grave. "The Golden Sage of Konoha breached the sanctuary. He slaughtered the clones, killed Madara, and buried the corpse under that stone."
"Well, that is incredibly inconvenient," Tobi mused, scratching the side of his swirling face. "What do we do now?"
"We recover the eyes," Black Zetsu commanded. He gestured toward the earthen mound with a dark, liquid appendage. "Bring the body out, Tobi. Break the seal and exhume him."
Tobi did not overthink the command. He possessed a simple, straightforward nature beneath his bizarre exterior. He walked over to the grave, completely oblivious to the intense, paranoid scrutiny Black Zetsu was applying to the surrounding bedrock.
Tobi placed his hands on the stone. He did not use a complex jutsu; he simply utilized his unique, plant-like physiology to merge with the earth, parting the soil and stone effortlessly.
The bedrock gave way.
Black Zetsu tensed, preparing to phase into the floor at the first sign of an explosive seal or a paralyzing array.
Nothing happened. The cavern remained entirely quiet.
Tobi reached into the hollow and hauled the frail, broken corpse of Madara Uchiha up from the dirt, laying him unceremoniously on the cavern floor next to the grave.
Black Zetsu let out a long, silent sigh of relief. His paranoia had been unfounded. The anomaly was powerful, but he was human. He had simply buried his enemy and left.
"He looks terrible," Tobi commented, poking Madara's chest.
"Do not play with the corpse," Black Zetsu snapped, sliding closer but still maintaining a cautious distance. "The Rinnegan were exhausted by Izanagi, but the visual prowess remains dormant within the tissue. If they are transplanted into a suitable host with Senju vitality, they can be reactivated. Remove the eyes, Tobi. Give them to me."
Tobi nodded. He reached down and unceremoniously plucked the two pale, spent eyes from Madara's skull. He held the small, fleshy orbs in his pale hand, turning toward the dark entity.
Black Zetsu extended a dark, shadowy hand to receive them.
"Here you go," Tobi said, dropping the Rinnegan into Black Zetsu's palm.
The moment the dark, alien flesh of Kaguya's will made physical contact with the eyes, the atmosphere in the cavern violently ruptured.
There was no explosion of fire. There was no crack of thunder.
It was a sudden, suffocating plunge into an absolute, crushing spiritual gravity. The temperature in the cavern plummeted to freezing in a single microsecond.
Nanami Kento had indeed left a trap. But it was not a sealing jutsu forged of chakra, nor was it a physical array carved into the stone. It was a Hatsu.
Abyssal Hound.
The beast had been sitting atop the grave the entire time, concealed perfectly by In—an advanced application of aura that rendered constructs entirely invisible and undetectable to all known sensory techniques and Dojutsu. It had remained perfectly stationary, a dormant predator waiting in the absolute silence of the void.
The activation condition was highly specific, forged through a binding vow: The concealment drops, and the execution initiates, only when a target possessing the lineage of the Ōtsutsuki physically touches the guarded object.
The condition was met. The In shattered.
Black Zetsu recoiled violently, his yellow eye widening in pure, unadulterated terror as the air above the grave tore open.
The Abyssal Hound materialized.
It was a terrifying, massive manifestation of lethal intent. It took the shape of a heavily muscled, lupine predator, roughly the size of a large warhorse. It possessed no physical fur. Its entire body was formed from hyper-condensed, pitch-black aura, appearing like shifting, solid shadow or thick, dark smoke that actively absorbed the ambient light of the cavern rather than reflecting it. Faint wisps of black aura constantly bled off its jagged edges like dark flames, instantly dissipating into the cold air.
It had no pupils or irises. Its eyes were narrow, hollow slits that glowed with a stark, empty white light.
But its most defining and dangerous feature was its maw. The jaw was slightly elongated, and as it opened its mouth in a silent, terrifying snarl, it revealed multiple rows of jagged, glowing, ethereal teeth. The inside of the mouth was a total, consuming void.
Tobi stumbled backward, tripping over his own feet, completely paralyzed by the sheer, overwhelming dread radiating from the construct.
Black Zetsu did not freeze. The ancient entity recognized the construct for what it was—an absolute, lethal counter designed specifically to bypass physical reality.
He dropped the Rinnegan and dove directly into the solid stone floor, attempting to merge with the earth and flee through the subterranean network.
The Abyssal Hound moved.
Despite its massive, heavily muscled build, it was entirely weightless. It left no footprints on the cavern floor. It made absolutely no sound as it sprinted forward. It was a shadow detached from the physical world.
The beast did not claw at the stone. It plunged its ethereal head directly into the solid bedrock, passing through the physical matter as if it were water.
Black Zetsu was fast, fleeing through the earth at a terrifying speed, but the Hound was faster. It did not track chakra; it tracked the specific spiritual essence it had been commanded to erase.
The beast closed the distance in the dark beneath the earth. It opened its massive, elongated jaws.
This was the core of the Hatsu, the ultimate ability that touched upon the rare affinity of Specialization: Soul Devour.
It was a technique fueled by an extreme, life-altering limitation. Nanami had forged a vow deep within his spirit. If he ever commanded the Abyssal Hound to use Soul Devour on a normal human, a standard shinobi, or any non-valid target, his aura nodes would permanently close, destroying his ability to use his power forever. This massive, absolute risk was the required fuel to allow the construct to perform erasure of an immortal soul.
The Hound's ethereal teeth snapped shut.
The jaws bypassed Black Zetsu's physical, fluid form completely. The glowing teeth latched directly onto the dark, ancient spiritual essence of Kaguya's will.
Deep beneath the earth, a silent, agonizing scream echoed in a realm beyond physical hearing.
The Hound ripped its head backward. It tore the soul entirely from the physical shadow. Black Zetsu's form lost all cohesion, dissolving instantly into a puddle of inert, lifeless black sludge within the rock.
The Abyssal Hound swallowed the essence, pulling the ancient will into the total void of its maw, erasing Black Zetsu from existence entirely.
The Forest Camp - The Present
Nanami Kento sat beside Tsunade, a cup of hot tea resting comfortably in his hands. The crackling campfire illuminated the small clearing, pushing back the evening chill.
Deep within his spirit, he felt the heavy, absolute resonance of his Vow engaging.
He felt the In drop. He felt the specific, conditional parameter trigger. And then, he felt the massive, sudden influx of dense spiritual energy as the Abyssal Hound successfully completed the Soul Devour.
Nanami slowly lowered his teacup, resting it back on his knee. He looked into the campfire, the flames reflecting brightly in his eyes.
A slow, knowing smirk spread across his face.
Tsunade, feeling the subtle shift in his demeanor, lifted her head from his shoulder. She looked at his face, catching the sharp glint in his eyes.
"What is it?" Tsunade asked softly, ensuring her voice didn't carry over to where Akira was distracted by a passing firefly.
Nanami turned to her, his expression returning to its usual, calm baseline.
"The trap I left at the grave has been triggered," Nanami informed her quietly. "The condition was met. The intended target has been successfully engaged and neutralized."
He brushed the dust from his dark trousers and adjusted the cuffs of his shirt.
"I need to return to the cavern to retrieve the assets and secure the site," Nanami said, his tone entirely professional. "I will be fast. Keep Akira close."
Tsunade nodded, her tactical instincts taking over. She did not ask further questions. "Understood. We will maintain the perimeter here."
"Hiraishin."
Zip.
He vanished from the quiet forest clearing.
A fraction of a second later, the sharp scent of ozone filled the cold, damp air of the subterranean cavern.
Nanami materialized near the edge of the subterranean pool. He quickly assessed the scene.
The earthen grave had been broken open. The frail, ruined corpse of Madara Uchiha lay unceremoniously on the dark stone floor. A few feet away, resting in the dust, were the two pale, spent orbs of the Rinnegan.
Standing near the cavern entrance, trembling violently, was a single White Zetsu clone encased in a swirling, mask-like carapace.
Tobi was entirely frozen in shock. He had just watched a massive, weightless shadow-beast materialize out of thin air, dive into the solid rock, and eradicate the immortal will of Black Zetsu without making a single sound.
When Nanami appeared in a flash of spatial distortion, Tobi let out a high-pitched yelp, throwing his hands up in a gesture of absolute surrender.
"I didn't do it!" Tobi babbled, his single eye wide with panic. "I just dug the hole! The black goo guy touched the eyes, and then the giant scary dog ate him! Please don't feed me to the dog!"
Nanami did not engage in conversation. He required the area secure, and he required intelligence.
He moved with immediate, clinical precision. He stepped forward, his hand dipping into his pouch. He unfurled a heavy, pre-prepared containment scroll, snapping it open with a sharp flick of his wrist.
"Wait, let's talk about—"
Nanami slammed his palm against Tobi's swirling chest, channeling a direct pulse of sealing chakra. The eccentric clone was instantly pulled into the parchment, bound tightly within the ink array. Nanami rolled the scroll shut, tying it off and securing it back in his pouch.
With the immediate perimeter clear, Nanami walked over to the corpse of the ancient Uchiha.
He unfurled a second, larger storage scroll. He carefully sealed the two Rinnegan into a seperate scroll. Then he performed the same sequence for Madara's physical body.
He rolled the heavy scroll closed, securing it tightly. The ultimate assets of the Warring States era were now safely in his possession, ready to be transported back to the secure vaults of Konoha.
As Nanami placed the scroll into his vest, the shadows in the corner of the cavern shifted.
The Abyssal Hound returned.
It phased silently through the solid bedrock wall, stepping into the dim light of the cavern. It made no sound as its paws touched the stone.
Nanami turned to face his creation.
The Hatsu had evolved.
The Hound was no longer the size of a warhorse. Having successfully devoured the ancient, incredibly dense spiritual essence of an Ōtsutsuki-lineage soul, the beast had absorbed the soul of its prey.
The Hound had physically swollen in height and mass. It now towered over Nanami, its massive, heavily muscled frame easily double its original size. The hyper-condensed, pitch-black aura that formed its body was thicker, absorbing the ambient light of the cavern so intensely that it looked like a walking void. The wisps of dark aura bleeding off its edges were more violent, rising like thick, black steam.
Its narrow, hollow slits stared down at Nanami, glowing with a stark, cold white light.
It was a terrifying, apocalyptic manifestation of lethal power.
Yet, as it stood before its creator, the massive beast lowered its elongated head slightly, remaining perfectly still, awaiting further commands.
"The execution was successful," Nanami noted quietly, observing the sheer volume of aura the Hound now commanded. "The primary architect of the shadows has been removed."
He understood the mechanics of his own Hatsu. The beast had absorbed enough energy to exceed its natural threshold. The next time it was deployed in combat, the Abyssal Division protocol would trigger, splitting the massive entity into two separate, coordinated hounds of immense power.
It was a formidable escalation of his arsenal, purchased with the permanent erasure of the world's deepest threat.
Nanami raised his right hand, pointing a single finger toward the massive beast.
"Return."
The Abyssal Hound did not make a sound. The pitch-black aura suddenly lost its cohesion, dissolving into a massive cloud of dark, ethereal smoke that rapidly condensed and flowed back into Nanami's extended hand, re-entering his spiritual coils.
The cavern was finally, truly empty.
There was no body, no hidden eyes, and no ancient entity lurking in the walls. The Mountain's Graveyard was nothing more than a hollow tomb of forgotten bones.
Nanami Kento adjusted the collar of his shirt. He performed a final, sweeping sensory check of the subterranean network, confirming the absolute absence of any lingering threats.
"Hiraishin."
He vanished from the darkness, leaving the ghosts of the past behind, and returning to the quiet forest clearing where his family waited by the fire.