The pursuing captains, Shinji Hirako and Kensei Muguruma, rushed toward the Senkaimon, their movements swift and urgent as they chased the shape-shifting fugitive. With time slipping away, they engaged Flash Step, tearing through the air at breakneck speed.
"Where did you encounter him?" Shinji's voice was steady, but there was a hint of tension.
"Near the rubble where I found Lieutenant Kuchiki injured. I don't think he's the one who did her in, though."
Shinji arched his brow. "And how can you tell?"
Kensei exhaled sharply. "There were no traces of his black substance when we moved her to safety."
Black substance?
Images of his own encounter with Mercer flashed through Shinji's mind, the grotesque tendrils, the unnatural way his biomass moved.
"Oh… that substance," he muttered with a nervous smile, before pushing further. "So, aside from nearly killing us, what else can he do?"
Kensei clenched his fists. "He's fast. Too fast. Smart, too. And... I don't know… he toyed us."
"That must've hurt your prideful heart," Shinji teased, masking his concern.
"Beat it. The last thing I noticed was that his fists turned into something about half the size of Yammy Llargo's hand."
The air between them grew heavier. Yammy Llargo—the Cero Espada. A monster who had been slain by Byakuya Kuchiki and Zaraki Kenpachi, but not before showcasing nightmarish power. If Mercer's strength was anywhere near that level…
They were halfway to the Senkaimon when a grotesque distortion rippled through the reiatsu in the air.
Shinji's stomach dropped. "Shit, we're too late."
"We need to move—now!"
The two captains burst into the Senkaimon courtyard, only to be greeted by a scene that sent an ice-cold chill down their spines.
Bodies. Everywhere.
The Kido Corps practitioners, who only moments ago stood as Soul Society's guardians, were now nothing more than mutilated husks. Twisted spikes of biomass jutted from the ground in a sickening display, some corpses still twitching, their limbs barely hanging on. The courtyard was drenched in blood, dark pools reflecting the flickering light of the Senkaimon gate.
A weak voice croaked amidst the carnage.
"Captain… help me…"
A barely-alive practitioner reached out to Shinji, his body impaled through the torso, his eyes filled with terror. He wasn't pleading for rescue—he was begging for release.
Kensei swallowed hard, forcing down the bile rising in his throat. Mercer had held back against him earlier… and now he understood why. If he hadn't, Kensei would've been just another corpse in this massacre.
Shinji, however, wasn't just shaken—he was enraged. His teeth ground together, his fingers curling tightly around his zanpakuto.
Mercer stood before the gate, his hands gripping the doors as he slowly pried them open. Even as they approached, he didn't turn to face them. His movements were eerily calm, calculated.
"Don't even try to follow me," he warned, his voice carrying an unsettling certainty.
Shinji took a step forward, defiance crackling in his reiatsu. "Are you strung up high or something? Why would we let you get away?"
Mercer's gaze finally flickered toward them, his crimson eyes locking onto Shinji. "Because if you value the lives of everyone here, you'll stay right where you are."
Kensei bristled at the threat, but before he could lunge, Shinji stretched out an arm, stopping him in his tracks.
"Fine," Shinji said suddenly. "You can walk away."
Kensei's eyes widened in disbelief. Shinji wasn't the type to surrender—not like this.
"I'll turn a blind eye to what happened here," Shinji continued, his voice steady but his grip on his sword tightening. "As long as you never return to Soul Society again."
Kensei's mind reeled. Shinji wasn't a fool—there had to be a trick.
A trick…
Wait… Mercer doesn't have a Jigokucho… which means…
His eyes shot toward the open gate.
He has to go through the Dangai.
Realization hit Kensei like a brick wall. Mercer had no way to navigate the Dangai safely. If he stepped through without a Hell Butterfly, he'd be at the mercy of the Kototsu—the very force meant to purge anomalies from the liminal space.
Mercer hesitated. Something wasn't right. He could feel it. Shinji had been staring him down with murderous intent only moments ago—why was he suddenly letting him go? His instincts screamed at him not to step forward.
"Leave," Shinji pressed, lifting his zanpakuto . "Before I change my mind." After a lingering moment, Mercer finally stepped into the light.
Shinji turned away, his face unreadable. Kensei, however, remained frozen, staring at the Senkaimon like a man watching a predator slip into the dark.
"To think you tricked him into entering the Dangai… I doubt he'll make it through Kototsu alive." Kensei exhaled, rubbing his face.
Shinji didn't respond immediately. His usual laid-back smirk was nowhere to be seen. "That was just a gamble of mine, big lug," he muttered, voice laced with unease. Kensei bristled at the nickname, but let it slide. For once, he was too rattled to snap back.
"That look he gave us before stepping through..." Shinji finally admitted, voice lower now. "It reminded me of Aizen Sousuke."
Kensei stiffened.
"What are you saying?"
Shinji hesitated, then exhaled. "Rumors say that, after Aizen took in the Hogyoku, he destroyed the Kototsu like it was nothing. That day, when we fought him… we were helpless. I couldn't gauge Mercer's reiatsu properly, but judging by his abilities alone…" He trailed off.
Kensei's stomach twisted. "You think he's as strong as Aizen?"
Shinji gave a small, humorless chuckle. "Possibly."
Silence stretched between them as they began walking away from the blood-soaked courtyard. The Senkaimon loomed behind them, its light flickering ominously.
Kensei exhaled, still unsettled. "And if Mercer does find his way out of the Dangai?"
Shinji closed his eyes for a brief moment, then gave him a look of quiet defeat.
"Then… we may have just condemned the Human World to death."
Mercer took a step forward into the abyssal void of the Dangai, a realm stretching infinitely beyond what the eye could perceive. The air felt thick, pressing against his body like an unseen force attempting to smother his existence. Towering walls, slick and pulsating with an eerie glow, bore the remnants of countless souls that had been swallowed by time itself. Bones, blackened and brittle, were embedded within the walls, some still eerily clinging to the last shreds of their former selves. Faint, whispering echoes of the dead swirled in the stagnant air, barely audible yet ever-present.
From the fragments of knowledge he had devoured, Mercer recognized this place. The Precipice World. The Dangai. A space that served as a tether between the Human World and Soul Society, where time was an unforgiving enigma. Here, an hour in the outside world stretched into two thousand years. An eternity trapped in this forsaken corridor would be akin to a fate worse than death. However, Mercer was not bound by mortal limitations. Time had no hold over him. He could walk this endless void for centuries, and it would not matter.
His thoughts were interrupted by a flicker of golden light at the far end of the tunnel. It was distant but growing, pulsing with unnatural intensity. Then, a tremor. The walls quivered, and the very ground beneath him vibrated as the light hurtled toward him with a deafening roar. Within moments, its form took shape—a monstrous, shadowy entity enveloped in a blinding, golden aura. A spectral train, neither alive nor inanimate, barreled toward him at impossible speed. This was it—the Kototsu. The enforcer of the Dangai. A relentless, mindless executioner that erased all who trespassed.
A grin formed on Mercer's face. "Perhaps I can stop this thing."
His arms warped, stretching and swelling grotesquely as jagged, monstrous Hammerfists replaced his hands. The black-red tendrils crackled as they solidified into a brutal, armored mass. He slammed them together, the impact reverberating like a war drum through the endless corridor.
Then a thought crept into his mind.
How long is this thing?
He spread his monstrous limbs wide, his body shifting into a battle stance as he prepared for the collision. The Kototsu shrieked as it neared, its massive form blotting out all light, an impending calamity that sought to erase him from existence.
BAM !!!
The impact sent a shockwave through the Dangai. Mercer's feet dug into the ground, dragging deep trenches as the sheer force of the Kototsu pushed him backward. His enhanced strength, which had shattered tanks and torn through steel like paper, was now pitted against something far beyond mortal comprehension. The train's incorporeal body refused to be restrained. It surged forward, heedless of the obstruction in its path.
"Tch." Mercer scowled. "Tough bastard."
Realizing brute force alone wouldn't suffice, he made a split-second decision. His form liquefied, cascading into an inky black tide that surged forward, enveloping the spectral behemoth in its writhing mass. The Kototsu roared in protest, but Mercer did not relent. His biomass slithered into every crevice, sinking into its ethereal framework like a parasite worming into its host. He felt the entity resist, a primal force that refused to yield.
But Mercer was patient.
Thirty minutes passed before the Kototsu's thrashing weakened. An hour more, and its once blinding glow dimmed into nothingness. With one final, agonized shriek, it ceased all resistance. The golden light flickered out, and the last remnants of the Kototsu were consumed. Mercer stood once more, his form solidifying, his irises gleaming with a haunting, golden glow.
A grin spread across his lips. He had done more than consume it. He had become it.
He crouched, placing his palm against the pulsating ground. Tendrils coiled outward, injecting his biomass into the very fabric of the Dangai. He could feel it now—an awareness of the space around him, of the temporal veins that stitched this world together. The knowledge filled his mind like an ancient scripture unveiling itself.
A tremor. A deep rumble. Then, from the depths of the Precipice World, something emerged.
A hulking form slithered forth, its structure bending and reforming, until it took shape. A monstrous train of pure biomass, twisted and grotesque, lined with pulsing veins of black and crimson. Its exterior bore the distorted remnants of the Kototsu's former self, fused with Mercer's own organic terror. A bright, ominous glow surged from the crest of the train, casting a blood-red hue upon the walls of the Dangai.
Mercer tilted his head, watching his creation with mild amusement. He extended a single finger and uttered a command.
"Smash the gate to Soul Society."
The crimson glow pulsed wildly before plunging into the monstrous engine, igniting its core. The silence shattered as the creature's engines revved—a hellish screeching that reverberated through the Precipice World. The sound escalated, growing louder and more feral, until, with a monstrous lurch, the train surged forward. It started slow, then picked up speed, faster,
faster, until it roared down the corridor like an unshackled demon, its singular purpose to obliterate whatever lay in its path.
Mercer, satisfied, turned his gaze ahead. The end of the tunnel was near—a gateway of light flickering in the distance. Without hesitation, he extended his Whipfists, latching onto the shifting walls, and launched himself toward the exit. The darkness of the Dangai shrank behind him, swallowed by the insatiable horror he had left in its wake.
He was returning to the world of the living.
Where he would emerge, however… was another mystery entirely.