The human and beast pair stood before a massive, maw-like entrance to the cave system. Their long training journey had brought them here, and once they explored the depths, they could finally return.

  Kai enjoyed traveling with Umbra. Over time, they had grown close, like a true family. Yet, his vigilance never waned. Constantly scanning their surroundings had worn him down. His spirit sense had sharpened from overuse, but mentally, he was exhausted. He couldn’t truly relax, not knowing what monstrosity might leap out at any moment.

  Umbra, on the other hand, was thriving. For the first time, she had a companion strong enough to fight beside her. She relished every battle, every chance to hone her skills. If this continued, she believed she might finally have her revenge. She would never be toyed with again.

  Together, they stepped into the cave, senses sharpened, ready for anything.

  ***

  Inside, the air was damp and heavy. Darkness clung to the walls, and an eerie silence enveloped them. Only the faint glow of moss on the ground offered light. Thankfully, their spirit sense kept them aware of their surroundings.

  Deeper in, the fluttering of wings echoed through the cavern, followed by random screeches. Insects skittered across the floor as the pair moved cautiously.

  Kai felt something unnatural in the atmosphere, an oppressive weight, but couldn’t pinpoint its source.

  They advanced slowly, every step deliberate.

  Suddenly, Kai sensed movement a hundred meters ahead. Hanging from the ceiling was a cluster of massive, vampiric creatures, Darkness Vampyr Bats. These beasts fed on life force and mana, using dark energy to grow stronger. They were deadly.

  Umbra melted into the shadows, her presence vanishing. Kai crept forward, blade in hand, cloaked in dark green mana to avoid detection.

  As he neared, the bats’ eyes snapped open. It was as if they had been waiting. Eight towering beasts, each two meters tall, launched from the ceiling, shrieking. The sound carried echoes of dark mana, disorienting him. His ears pulsed, his mind dulled, his mana in chaos, as he stumbled.

  Umbra struck from behind, her claws slicing through the air, each swipe trailing cold-burning darkfire. The first bat was torn apart. The remaining seven retaliated, spitting beams of pure darkness. One struck Umbra, slamming her into the cavern wall. She spat blood, her insides scrambled, she collapsed to the ground.

  A bat hovered over her, its mouth wide and pulsing. It began siphoning her mana, the darkfire on her coat pulled into its maw like smoke into a vacuum.

  Only ten seconds had passed since Kai was hit. He urged his twin serpents to circulate faster, pumping poison and water mana through his body, purging the corrosive dark energy.

  He coiled his lower body and launched forward, slashing with twin-colored sword light. His blades tore through two bats mid-air, their bodies twisting and collapsing in mangled heaps.

  But two more unleashed sonic waves, slamming into his chest. He staggered, coughing blood. The pressure was immense, like being crushed by invisible hands.

  Another bat dove at him, claws extended, aiming for his neck.

  Kai surged with moonlight. A faint crescent tattoo on his chest glowed; he had managed to barely form a light outline of the moon during the last month, which channeled energy through his body.

  His water membrane hardened with pale light. The bat struck his head, driving him into the ground, but Kai rose shortly after from the ground, battered but unharmed. The bat hovered above in shock.

  Meanwhile, the strongest bat continued siphoning Umbra’s mana. Then something unexpected happened. Its body began to burn from within.

  Umbra’s darkfire had evolved, infused with a hint of true fire. Her recent diet of red cores had altered her mana, and the moonlight she had absorbed from Soulberry fruits had awakened a rare affinity just as it did for Kai, the elemental fusion. Her mana now burned hot and cold, devouring both life and energy.

  She had let the bat feed on her, on purpose.

  Umbra’s eyes snapped open, blazing with fury. She launched upward; her beak covered in darkfire. It pierced the bat’s skull, which exploded in a rain of gore and flame.

  She landed with a snarl and jumped straight back up, body growing in midair, her paw now massive and glowing.

  With a single swipe, she crushed another bat like a bug, its bones cracking under the force.

  Three remained.

  Kai, now fully empowered, punched through one bat’s chest with a moonlight-infused fist, tearing him in half. The last two tried to flee, but it was too late. Kai struck mid-air with a tri-colored sword light. The blades sliced through the air, reducing the fleeing bats to mangled heaps on the cavern floor.

  The silence returned.

  He landed beside Umbra. Both were exhausted. They had barely entered the region and had already faced death.

  The bats had sensed Kai’s approach, but they hadn’t anticipated his strength, nor Umbra lurking in the shadows. Their ambush had failed, but the battle had been brutal.

  Kai landed beside Umbra, both panting, bloodied, but alive. The cave was littered with the remains of the Vampyr bats, their dark mana dissipating into the air.

  Kai crouched beside her, offering a faint smile.

  “You alright?”

  Umbra coughed, then chirped through the pain.

  “I let one of them feed on me while I recovered a bit. Figured it’d regret it.”

  Kai raised an eyebrow, glancing at the scorched remains of the bat.

  “You’re insane.”

  “Takes one to know one.” She happily replied.

  Kai chuckled, then winced.

  “I didn’t expect them to scream mana into my skull. Felt like my brain was melting, and my mana went wild.”

  Umbra leaned her head back, eyes half-lidded.

  “You held up. That moonlight tattoo… It’s stronger than I thought.”

  Kai looked down at the faint crescent on his chest.

  “Barely got it working. It’s still not ready, I’m not even on the first step.”

  Umbra’s gaze softened.

  “You’ve changed. Stronger. Sharper. You’re not just surviving anymore.”

  Kai nodded slowly.

  “Neither are you. That fire in your darkfire… It’s new.”

  “Soulberry fruits. Red cores. Something’s shifting. I feel… more,” she whispered.

  They sat in silence for a moment, the cave quiet except for the distant dripping of water.

  “We almost died back there.”

  “But we didn’t,” she cut him off.

  “Yeah. Still… we just entered this region. If this was the welcome party…”

  Umbra stood slowly, shaking off the dust.

  “Then let’s make sure the rest of them regret inviting us.”

  Kai grinned, rising to his feet.

  “You’re really enjoying this, aren’t you?”

  “I’ve waited too long to be strong enough. Now that I am… I’m not stopping.” She raised her head proudly.

  Kai handed her one of the cores.

  “Eat. Rest. We move when you’re ready.”

  Umbra took it, her eyes glowing faintly.

  “I’m grateful.”

  “We’re in this together.” He replied with a smile as he started collecting other cores. She will need them later.

  They paused to rest, gathering strength before venturing deeper into the unknown.

  ***

  Once they were back in fighting shape, Kai and Umbra charged deeper into the cave system, their senses sharp and weapons ready.

  The darkness was oppressive, but soon, glowing mushrooms began to dot the ground, blue and violet light pulsing like veins through the stone. The air was thick with spores, each breath heavy, but the bioluminescence carved a path through the gloom, turning the cave into a magical oasis.

  This book was originally published on Royal Road. Check it out there for the real experience.

  They slowed down to admire the sights and moved forward, slowly, ever careful.

  Suddenly.

  Two packs of Vampyr Bats descended from the ceiling, screeching as they launched their ambush. But Kai was faster. His blade flashed, slicing through the first wave before they could even reach him. Umbra struck from the shadows, her claws tearing through wings and bone. The bats were Tier 5, dangerous in numbers, but numbers meant nothing now. The pair moved like predators, coordinated and ruthless. Within seconds, the cave floor was littered with twitching corpses.

  Further in, they stumbled upon a narrow creek winding through the caverns, glowing faintly with mana. It flowed like a lifeline, guiding them deeper into the unknown. They followed it, never hesitating.

  Dark spiders lunged from the walls, spitting dark webs of corrosive mana. Kai spun, cleaving through their legs mid-air. Umbra pounced, crushing skulls with her beak, burning the webs like dry leaves with darkfire.

  A new pack of Bats appeared, their sound waves echoing as they dove towards Kai. Umbra spat thick beams of concentrated darkfire, leaving nothing but corpses behind her.

  Then came the Abyss Rattlesnakes.

  Blind, but deadly, they sensed mana like bloodhounds. One struck from the water, Kai dodged, countered, and drove his blade through its skull. Another coiled around Umbra, fangs dripping with venom. She roared, igniting her darkfire and incinerating it in a flash.

  The snakes were tougher, their venom potent, their movements unpredictable. But Kai and Umbra had grown stronger. Each fight sharpened their instincts, refined their synergy. The deeper they went, the faster they moved, the harder they hit.

  By the time they reached the next chamber, the caves behind them were a graveyard.

  ***

  They scanned the area, ready to fight, senses stretched thin. Nothing stirred.

  For now.

  Kai collapsed against the cold stone wall, his breath shallow, his mana spent. “I feel horrible,” he muttered. “It’s been hours of killing. I don’t even know what I’m becoming.”

  He stared at his blood-stained hands. In the beginning, every fight had felt like progress, proof that he was evolving, surviving. But now? Every corpse felt heavier. Every victory left a scar.

  “It’s either us or them,” Umbra said, her voice echoing in his mind, calm and detached. “They attacked first. We finished it.”

  Kai nodded slowly, but the weight didn’t lift. “I know. I just… I didn’t think it would feel like this. Like we’re erasing lives. Not just defending ourselves, invading their world.”

  “Survival doesn’t care about guilt,” Umbra replied. “And there’s nothing wrong with enjoying the kill.”

  Kai turned to her, eyes dark. “You sound like a killing monster sometimes.”

  Umbra snorted, a hint of pride in her tone.

  Kai looked away, his thoughts spiraling. He remembered the beasts they’d slain; some had attacked, yes. But others had simply been in the wrong place at the wrong time.

  He remembered the caves they’d entered, the territories they’d crossed. On Earth, he never had to question his morality like this. There were rules. Boundaries. Here, everything was survival. And survival was brutal.

  He thought of his parents. Were they searching for him? Did they miss him? Despite everything, they were still his family. Would he ever see them again? Would they even recognize him now?

  The guilt gnawed at him. Not just for the lives he’d taken, but for the life he’d left behind.

  Then the ground trembled.

  Kai’s spirit sense flared. Something massive stirred ahead.

  “Umbra,” he said, voice low.

  “I feel it,” she replied, her tone sharpening. “This one’s strong. Maybe the strongest yet.”

  Kai stood, gripping his sword tighter. “This might be our last fight on this trip.”

  Umbra’s eyes gleamed. “Then let’s make it count.”

  They stepped forward, side by side, one beast, one human.

  ***

  In the deepest chamber of the cave system, nestled within a jagged pit of stone and bone, coiled a monstrous centipede, ten meters long, its dark gold scales glinting like cursed treasure. Hundreds of crimson-tipped legs twitched in rhythm, each one sharp enough to pierce steel. At the front of its grotesque body, two massive pincer-like fangs clicked impatiently, sensing the disturbance rippling through its domain.

  This was no ordinary beast.

  A Royal Centipede, a Tier 8. A creature born of ancient bloodlines, feared across the jungle. If it survived long enough to evolve into a Divine Beast, it could awaken its ancestral power and ascend into a Sage Centipede, a being of near-limitless potential. But such evolution was rare. Their aggression often led to early death, and this one was no exception. Violent, territorial, and merciless.

  Its body shifted, legs scraping against stone as it rose from its coil, eyes glowing with primal fury.

  “Who dares intrude upon my territory and slaughter my subjects?!” the beast roared, its voice reverberating through the cave like thunder.

  The walls trembled. Dust fell from the ceiling. The air thickened with killing intent.

  It surged forward, a blur of gold and crimson, its rage boiling over. The intruders would pay. It would tear them apart, limb by limb, and feed their remains to the hatchlings buried beneath its lair.

  ***

  The roars tore through the cave system like a shockwave, shaking the walls and sending tremors through the stone. Lesser beasts scattered, diving into burrows and crevices, instinctively hiding from the fury of their ruler. The storm was coming, and they knew better than to be caught in its path.

  Kai and Umbra stood frozen as the voice echoed toward them, ancient and furious.

  “Who dares intrude upon my territory and slaughter my subjects?!”

  Kai’s heart skipped a beat. “It can speak… That means it’s at least a Tier 7,” he said, voice tight with dread.

  Umbra nodded, her tone grim. “Yes. And that means spells, intelligence, and bloodline power. This isn’t just another beast. This is a general.”

  Kai clenched his fists. He had faced monsters before, but this felt different. This wasn’t just survival; this was a reckoning.

  “We need to prepare for the worst,” Umbra said, her voice steady but low. “If things go south, you run. I’ll stall it. I might be able to escape through the shadows after you.”

  “No!” Kai snapped, his voice cracking. “No way. We fight together or we run together. I’m not losing you here.”

  Umbra turned to him, her eyes unreadable. She had accepted death before. But Kai hadn’t. Not yet.

  He stepped closer, voice trembling. “I’ve lost enough. I don’t even know if I’ll ever see my family again. I don’t know if they’re looking for me, or if they’ve already given up. But you, you're all I have now. If I lose you too…”

  He couldn’t finish the sentence.

  Umbra didn’t speak. Instead, she cloaked herself in darkfire, hot and cold flames swirling around her body. Her form expanded, growing to nearly four meters, her aura pulsing with raw power.

  Kai gripped his sword tighter, his core spinning faster, mana surging through his veins. He could feel the pressure building, the weight of the incoming threat pressing down on them like a tidal wave.

  They couldn’t outrun it. Not here. Not in its own lair.

  They needed to fight.

  ***

  The cave erupted in a thunderous explosion, rubble flying in all directions as an enormous gold-red centipede burst forth. Its armored body coiled upward, towering like a living fortress, eyes burning with fury.

  “You dare trespass in my domain and slaughter my minions?! You shall die for your arrogance!” the general roared, its voice shaking the cavern walls.

  Kai stepped forward, trying to reason with the beast. “We didn’t know this was your territory. We don’t want to fight. Just let us go.”

  The centipede’s laughter was hideous, echoing like a death knell. “Let you go? Why would I, when I can crush you like insects and feast on your remains?”

  Kai didn’t wait. He surged forward, coiling mana into his legs and launching himself like a serpent. His body glowed with blue and white light, and his sword materialized in his hands, moonlight spilling from the blade, illuminating the background.

  He struck first, his blade slamming into the centipede’s armored body, forcing it back several meters. At the same moment, Umbra lunged from the side, her claws cloaked in darkfire. She slashed through the air, sending condensed lines of mana screaming toward the beast’s face.

  The general roared, its body pulsing with mana. A shockwave burst from its core, scattering Kai and deflecting Umbra’s attack.

  “Not bad. You might actually make this fun.” It grinned, then opened its maw and unleashed a barrage of venomous geysers. The ground hissed as the poison splashed across the stone, turning it into a bubbling, toxic swamp.

  Umbra leapt to evade, but the centipede’s massive lower body whipped around, striking her mid-air and slamming her into the cavern wall. She screamed, her darkfire cloak flaring to absorb the impact, but the blow still sent cracks through her defenses.

  Kai hit the ground hard, already channeling his poison serpent. The venom surged through his body, burning like acid, but the serpent spun faster, absorbing and neutralizing the poison. He had trained for this. He had adapted.

  He saw Umbra struggling, pinned down by the centipede’s relentless assault.

  No time to hesitate.

  Kai charged, venomous mana coiling around his blade like a living snake. He struck between the golden plates of the centipede’s armor, driving the blade deep and injecting his mana into the wound.

  The general shrieked, recoiling violently. “You dare poison the king of all poisons?! Fool!” it bellowed, forcing the venom out with a pulse of mana.

  Kai landed beside Umbra, placing a hand on her back. He drew the poison from her body, his serpents spinning wildly to cleanse her. She growled, then vanished into the shadows.

  The centipede snarled and summoned a massive magic circle beneath its body. From it, a swarm of smaller centipedes erupted, hundreds, maybe thousands, flooding the chamber.

  They swarmed Kai, burying him in a writhing tide of legs and fangs. His three-colored mana shield held, but the pressure was suffocating.

  He activated his barely visible crescent moon tattoo. His body surged with power. The twin serpents around his core spun into a blur, and even the silver serpent stirred, coiling around the Soul Sword.

  Mana flooded his body, pushing his channels to the brink.

  Then he detonated it.

  A shockwave of raw energy exploded outward, vaporizing the swarm in an instant. The chamber was painted in blood and shattered carapaces.

  The survivors tried to flee, but Umbra struck from above, a meteor of darkfire crashing down and incinerating them.

  The general screamed in rage. It lunged, venom dripping, jaws snapping around Umbra, venom pouring into her body. She shrieked, shrinking her form to escape, but not before the fangs pierced deep.

  She hit the ground, twitching, her body riddled with venom. She wouldn’t go down like this, she roared. She poured as much mana as she could handle and launched a massive beam of pure concentrated darkfire, burning half of the centipede's armor off.

  Then she collapsed. Her darkfire flickered weakly as she fought to stay alive.

  Kai froze. Their soulbond flickered, faint, fading.

  His heart shattered.

  “You’ll pay for this!” he roared, leaping with everything he had left.

  He poured all his mana into his blade, water, poison, and moonlight until the three colors merged into a single, blinding azure light. He slashed.

  The strike tore through countless centipedes’ legs, ripping the other half of the golden plates from its body.

  The general howled. “Aura?! How can you wield aura?!” Panic crept into its voice; he even ignored the pain of losing his legs and armor.

  Then the centipede unleashed its final spell; there was no room for playing anymore.

  Magic circles erupted across the chamber, glowing with ancient venomous runes. The life force of every dead and even living centipede was siphoned into the general’s body. Its wounds sealed instantly. Armor regrew, thickened, and sprouted jagged, venom-coated spikes.

  With a deafening roar, the beast coiled into a massive, pulsating wheel of death, its body burning with toxic heat, its countless legs spinning like blades. Then it rolled forward, a living storm of destruction, ready to crush everything in its path.

  It rolled toward Kai like a collapsing star.

  Kai dropped to one knee. He had nothing left. His core was empty. His body broken. Umbra was dying.

  “It can’t end like this,” he whispered.

  He reached deep, into memory, into his soul. He remembered the Dawnbreaker. The Moonlit Dance. The scene of him killing thousands of enemies, while flowing through the battlefield.

  He couldn’t activate the full technique yet. But maybe… just one thread. It could be enough.

  He forced his newfound aura skill to activate. Azure light flared around his blade. He summoned every drop of moonlight mana he had left. His tattoo burned. His core screamed as he mimicked the Dawnbreaker's move.

  The golden wheel closed in.

  Kai slashed upward, slow, deliberate.

  A man and his sword.

  A single thread of moonlight formed.

  It met the beast.

  Slice.

  Silence.

  The centipede’s body split apart, collapsing in a heap of shattered armor and twitching limbs. Kai’s sword crumbled to dust.

  He turned towards Umbra.

  With little energy he had left, he crawled through the blood-soaked dirt to Umbra, barely breathing. He wrapped his arms around her, whispering her name.

  “Please… don’t go.”

  He begged his serpents to spin, to draw the poison out, to push healing water into her core.

  They obeyed.

  His core ran dry. His channels cracked.

  But Umbra’s breath steadied, and Kai collapsed beside her, unconscious, but victorious.