I Reincarnated as a Demon King,I Will Kill Everything

The corridor descended, lit by unlit torches—only absorbing the light. The air was cold, heavy, with a metallic smell—not of blood, but of spirits. We entered a circular chamber: the sigil holes in the floor spun slowly; in the center, Zereth lay on an obsidian altar, his body intact but his tattered shadow scattered across the floor like torn rags.

Selena lowered her head, then stepped aside—leaving my path clear.

I approached. "Zereth."

His eyelids trembled, unopened. His lips were cracked—not from heat, but from silence. From his chest, three cracks of pale light crept—like foreign letters forced into an ancient carving.

Noa whispered, "Lunar sign. Weak—but it penetrates right to the knot of the name. If left unchecked, the soul anchor will lose its 'first word.'"

I reached for the altar, suppressing a shiver. "Selena, close the door. Algor, Simon—begin."

Simon struck the iron gong—the Crucible hissed, black smoke rising from the cracks in the floor. Algor readied the Loom of Amon: the thread frame was invisible, just a flicker of movement in the air.

"Clarissa," I said without looking up. "Your blood."

The vampire stepped forward, biting her own wrist without hesitation. Her blood fell into the hollow—dark, sweet, cold.

"This isn't for his body," I explained. "We need a soothing cold—not a compelling heat."

Rena closed her eyes, activating a narrow Chaos Domain, just to dull the remaining lunar radiation in the room.

I raised Noa—gems 2 and 5 glowed softly.

"Begin," I said.

Algor weaved the lunar fissures with invisible thread. Simon hammered names—not flesh—solidifying the edges of the cracks so they would knit. Clarissa dripped vampire blood onto the knots, calming the frantic waves of Zereth's soul. Rena placed a ring of moon ash to form a support to keep the stitches from "stretching" out.

Noa resonated, guiding the rhythm. "Sew—two beats. Temper—one. Cool—hold."

We moved like an ancient demonic machine revived.

The first crack coalesced. The shadows on the floor shrank from four rips to three, then two.

Zereth sighed—a sound I'd only heard when the war was over. "My… Lord…"

"Silence," I said softly. "You'll be angry again later."

The second crack blossomed, lashing back. The lunar knot spewed a white torrent, trying to seal our route from within.

Rena groaned, her blood dripping to the floor. "I will extinguish it." She added Chaos; a ring of darkness swallowed the harsh light—just enough to create a gap.

"Now," Selena called from the door—the perimeter sigil trembling. "There is—external pressure. Not an enemy. Nysha returns."

A shadow crept from the threshold—Nysha knelt, offering a blue crystal that sighed softly. "Shard of Storm—a remnant of Darrius."

I grasped it. Lightning ions stung my palm—the residue of Darius's final trajectory.

"Noa," I whispered.

"Minimal integration, inject as a staple."

I pressed the shard against the edge of the second crack, then hammered with my palm. Ions electrified—the crack clung—the stitches clicked like a key finding a lock.

The third crack—the one holding the first word—was a hair's breadth away.

"This is the decisive one," Algor hissed, his blood dripping.

I placed Noa directly above the knot, summoning the remnants of the black moon, the darkness, and… the faintest trace of celes light that still lingered on my mask.

"Calm" I said to the altar—or to my own anger. "Until it's over."

[BLACK MOON SUTURE]

[BOOST]

An invisible needle stabbed; an invisible thread pulled. A voice—not a sound—shrieked inside our heads, like ancient letters refusing to be spoken. Then, slowly, it died away.

Silence.

Noa sighed—or made me sigh. "Soul integrity: 78% up. Anchor stable. Remaining wound: superficial."

Selena slumped her shoulders, Rena nearly collapsed, held by Clarissa. Algor burst into a fit of guffaws—a humiliating and beautiful relief. Simon rubbed the Crucible which was slowly cooling.

I placed a palm on Zereth's chest. "Open your eyes."

They opened halfway. My loyal demon eyes stared—still dark, but intact.

"Thank you… My Lord." His voice was hoarse, but it was Zereth's.

I smiled lopsidedly. "You owe me a new arm."

Zereth chuckled—barely audible. "I'll take it from the next enemy."

Selena looked at me. "Next orders?"

I weighed the aching pain throughout my body, Kravius's promise, and the church bells that seemed to still echo from the human world.

"Three days," I said. "We're not sleeping. Gravity training continues—half weight. Simon, make a Soul Splint for Zereth. Algor, write down the sewing pattern—this will be the standard for the next war. Nysha, you guard the door outside—if any divine eyes peek, remove it."

"Understood."

I turned to Rena. Her blood stained the stone. She didn't complain, just stared at me, waiting.

"You're coming with me," I said. "We need to synchronize before the High Cathedral. Kravius ​​gave the date—meaning the trap is set."

Rena nodded. "If he wants the stage, we'll bring it—our own fire."

I stared at the Undercrypt ceiling, feeling the castle's breath pulsate with our own. Two hero pillars fell; the sword that tormented me appeared with an invitation.

"Hell," I whispered, "is just getting warmed up."

The Undercrypt chamber had fallen silent as we began the healing phase—no longer sealing the cracks, but restoring Zereth's soul function and preparing his new vessel.

I lowered my palm to Zereth's chest. Noa Genesis pulsed softly.

"Noa, we'll begin with rhythm stabilization," I said.

"Acknowledged. Subject's soul resonance is unstable at 0.73. Suggesting a calming net," Noa replied heavily.

I took a breath, uniting the darkness—and the tamed remnants of the moon—into a low tone.

[BLACK MOON LULLABY]

A dark tone crept through the altar. The stitched fractures ceased to vibrate, and Zereth's shadow-heart rhythm began to sync at 0.92. His eyes—though closed—were calm.

"Simon," I called.

The blacksmith stepped forward with an obsidian tray containing a freshly soldered soul splint: a frame of Stygian Amber coated with bitter-scented Nightshade Myrrh.

"The Soul Splint is ready, My Lord."

"Install it at the second and third knot junction. Secure it with three dross nails—do not penetrate the core."

Simon nodded. His hammering was gentle—not striking flesh, but tapping the name to allow the splint to adhere. Each tap was accompanied by a grunt from Noah, ensuring the right pressure.

"Integrity up to 83%," Noa reported. "Anchor stability: solid."

I turned to Algor. "You hold the Loom of Amon. We'll tighten the Name-knot at the starting knot. Use Rena's moon ash as a safety ring."

Algor leaned forward, his hands moving through the air as if weaving invisible silk. The name-knot—which we could only feel as temperature—was gently pulled; Rena's moon ash ring framed the knot to keep it from stretching.

[NAME-KNOT: SILENT LIGATURE]

The knot was locked. The world's voices seemed to shrink in half. The micro-wounds at the edges of the name died away.

"86%," Noa murmured. "We can move on to the vessel."

I tilted my face to Zereth. "Now your arm."

I exchanged a silence for permission. He didn't speak, but the soul I'd silenced gave its assent.

"Simon, prepare the Ossuary Lattice for the bone—use a high-grade demonbone fragment. We'll use this for the nerve core." I held up a small Shard of Storm—Darius's lightning ions that we'd used as staples—now cut to a hair's length.

"Storm in Zereth's arm?" Selena raised an eyebrow.

"I softened the ions," I replied. "Not as a weapon, but as an impulse pathway. He needs a response faster than I can imagine."

Rena held the wound in her stomach, keeping a close eye on the seal's perimeter. "I can keep up with the remaining wild sacred if I jump."

"Don't use holy," I said. "It's residual pathing—I don't want the Church runes sticking."

We worked.

Simon assembled the bone framework at the base of the shoulder; Algor linked the Storm-Nerve to the arm's soul node; Clarissa dripped three drops of vampire blood—diluted one to nine—to cool the nerve pathways so they wouldn't shock the anchor.

I covered the assembly with Noa's palm, summoning darkness as a blanket.

[STORM-NERVE GRAFT]

[ANIMA SPLINT]

Pain screamed from the altar—not Zereth's voice, but a memory we didn't want to relive. I stifled it with the same Lullaby, forcing the fight away from the operating table.

"Response?" I asked.

Noah pulsed. "Conductivity 0.81 rising to 0.88. No lunar interference. Motor readiness: provisional 43%."

"Enough to bond," I said. "We synchronize."

I pressed my forehead to the back of Zereth's hand—a long-standing tradition of war demons, linking the beat of two fields.

[SYNCHRO PULSE]

My soul pulse dropped, his pulse rose. Two lines became one—not perfect, but strong enough to force the new frame to accept Zereth's name.

The arm—originally dust and design—began to take shape: black, covered in faint patterns reminiscent of lightning embraced by the night. His fingers moved once, reflexively—then still.

"92%," Noa said softly. "Stability: high. Locking: successful."

I released a breath I hadn't realized I was holding. The sting in my own shoulder rebuked me, but I let it go.

"Clarissa," I said. "Two more drops—on the shoulder knot. Save the rest. Zereth must not thirst."

"Yes, My Lord." The vampire shifted, meeting her red eyes faithfully.

Rena took a half step closer, still faithfully guarding the boundaries of the domain. "Can he wake up?"

"Can he wake up?" Noa replied. "Fighting… no. It took two nights of rebonding."

I looked at my old friend. "Did you hear?"

Zereth's eyelids trembled. "Your orders… my laws."

I let out a short laugh. "You're going to curse at me tomorrow at practice—so save your energy."

Simon closed the Crucible, letting the heat die down. Algor cleans the Loom with prayer cloths stolen from human altars—an irony we love. Selena signaled: safe corridor, core troops on guard.

"Take him to the Lower East treatment room," I ordered. "Put a second Soul Splint in the third hour, check the rhythm every hour. If the rhythm drops below 0.85, wake me up."

"Ready, My Lord," they answered simultaneously.

When the altar bearer lifted Zereth, his new arm reacted subtly—the index finger twitched, as if speaking life without words. He turned slightly to me; enough to see a shadow of respect in the corner of his eyes.

"Thank you," he whispered.

"Don't make me regret it," I replied.

They took Zereth away. The Undercrypt returned to calm, only the remaining sigil lines slowly evaporating.

Rena leaned back against the pillar, her blood staining the stone. "My Lord… your arm."

I saw the crack in my Overlord, the black blood beginning to dry. "Later, Him first."

Rena held back a smile—tired, but proud. "Okay."

I looked at Noa. "Recap."

"Subject Zereth: stable. Soul integrity 92%, arm motor 43% (natural increase). Lunar residue risk: low. Recommendations: abstain from holy magic, light shadow stimulation."

I nodded. "Let's make this a blueprint for field healing. Starting today—our forces will not only know how to kill, but also how to rebond."

Rena straightened, holding her wound. "And what about us?"

I looked up—through the stone and blood—imagining the spire of the cathedral called Kravius.

"We sleep for an hour," I said. "After that… we teach the world what it feels like to be reforged."

The Undercrypt responded with a low hum—like the half of the night giving its assent. In the distance, the ancient bells of hell tolled once, heavily.

Zereth breathed calmly. The troops moved again. And I—for the first time since the war began—allowed my eyelids to droop for a moment.