Kai lay stretched beneath a massive, uprooted tree, its roots twisting into the air like the bleached ribs of a long-dead beast. The shade was uneven, fractured by deep slashes in the earth left behind by earlier spells, but it was quiet. It was finally quiet enough for him to indulge in the only thing he actually cared about: inspecting the flute he'd just risked his spine to acquire.
The Lullaby.
He turned it over in his hands, letting the dim evening light glide across its carved surface. The dark wood shimmered with a faint, oily luminescence—the unmistakable hallmark of living magic wood. It wasn't common, and it certainly wasn't cheap. The material was incredibly dense with ethernano and naturally resilient to most physical trauma.
"The material is solid," he murmured, tapping the wood with a knuckle. "Very solid. It's just a shame the craftsman was apparently blind, drunk, or both."
The flute was crude. It wasn't ancient-ruin elegant, nor was it cursed-item sinister—it was just plain ugly. It was the specific kind of aesthetic disaster that offended Kai as a craftsman on a deeply personal, spiritual level.
"Three skulls? Really?" He squinted at the mouthpiece. "This isn't even a proper flute. It's a whistle. It looks like someone fed high-quality materials to an ugly tree and forced it to vomit up a whistle."
He flicked the wood lightly. "A very loud whistle. No wonder people died. They probably clawed their own ears out from how awful you looked."
A faint pulse of purple light flickered across the carved skulls.
Kai blinked. "Did… did you just pout?"
The Lullaby vibrated faintly against his palms, as if deeply insulted.
"Oh, so you do have feelings." Kai snorted. "Figures. Zeref's stuff always comes with an attitude problem. Don't look at me like that, you can blame your creator for making you an eyesore."
He dug into his coat, reaching deep into his pouch—his actual, non-a-pouch spatial storage tool—and pulled out a leather-bound notebook, a set of fine metal picks, and an ink pen. Pages flipped rapidly under his fingers, revealing hand-sketched diagrams of recovered artifacts, lacrima neural networks, and intricate rune arrays. It was his living archive.
Setting the flute down gently on his lap, he began to sketch. He mapped every rune etched into the wood, traced the microscopic channels where magic was designed to flow, and carefully marked the structural imperfections. The day slid quietly into dusk, and dusk dissolved into a crisp, cool night.
Kai didn't move. He had absolutely no intention of trekking back into town while carrying an active relic that kept whispering murder in the back of his mind. Better to stay in an already-destroyed wasteland where the worst potential casualty was a tree that was already dead.
As the hours bled away, the whispers grew more distinct.
Break them… rip them apart… play me… let them scream…
Kai rubbed his ear, his pen never stopping. "You nag more than Erza. Shut up, I'm working."
The purple glow pulsed with indignant heat. He ignored it completely.
Finally, with a long, satisfied exhale, he leaned back against the roots. The blueprint was complete. Runes mapped, internal architecture understood, and the flute's theoretical weaknesses laid bare. More importantly, he now had the exact magical schematic recorded in his archive—plenty of data to reverse-engineer these specific compliance techniques later.
He snapped the notebook shut. "Alright. Time for a little invasive surgery."
Flexing his fingers, he held the flute securely between his palms.
"Tinkerer Magic: Dismantle."
His hands flared with a brilliant, clockwork gold. Thread-like lines of magic wove between his fingers like a spiderweb of light, sinking deep into the wood—
—until the flute convulsed with a violent, oily surge of purple energy.
"Uh-oh."
The wood cracked open like an eggshell. A thick, suffocating mass of pure shadow burst free, instantly spinning into a localized vortex. The resulting magical shockwave hit Kai like a runaway carriage, throwing him backward. He skidded across the dirt and loose rocks, coughing as a localized explosion of dust completely obscured his vision.
He sat up, wheezing heavily. "Okay… yeah. That one's on me."
When he looked through the settling haze, a hulking silhouette had already risen ten meters into the air. It was a monstrous, humanoid titan, built like a malformed corpse carved out of solid smoke. Its ribs protruded from its chest like jagged, purple blades. Its stomach was entirely hollowed out—a gaping, abyssal hole humming with interlocking runic circles. Its face was a twisted, elongated skull, and its aura pressed down on the clearing until the very grass beneath it began to wilt.
The demon flexed its clawed hands, dark lightning crackling across its knuckles.
"So," Kai muttered, brushing the loose dirt off his shirt. His voice was entirely devoid of fear, replaced entirely by a profound, exhaustion-fueled annoyance. "You got… big."
The monster roared. The ground trembled, and the low-hanging clouds seemed to warp away from the sheer pressure of the sound.
"I have waited…" the creature hissed, its voice scraping together like rusted iron plates. "Waited and waited in the dark… for you pathetic wizards to play me! To unleash my song! To drown this world in beautiful screams!"
Kai raised a single, unimpressed eyebrow. "Right. Theatrical melodrama. Do keep going."
If nothing else, the villain monologue was giving him time to think. He wasn't anywhere near full strength; his wounds from his previous fights had barely closed, and his magic pool was running on fumes, but he had just enough left for a proper scrap.
"You!" The demon jabbed a massive, shadow-carved talon directly at him. "You dared attempt to unmake me! You shall be the first soul harvested in my grand new symphony! Be grateful, worm… that the Lullaby begins with you!"
Kai blinked slowly. He dragged himself to his feet, let out a massive sigh, and reached back into his storage pouch.
"Look, I'm injured, I'm exhausted, my reserves are shot, and I am mentally completely unprepared for a third-rate monologue," he said flatly, his arm buried up to the elbow in his pouch. "Just give me a second."
He pulled out a handful of metal discs, a tuft of cotton, a low-grade acoustic lacrima, two short copper wires, a piece of magically treated sponge, and a single brass screw.
"What are you doing?!" the monster demanded, its booming voice wavering slightly as Kai completely tuned it out.
"Preparing," Kai replied, his fingers moving with a terrifying, blurred dexterity as he assembled the components. "You know. Like a responsible adult."
"YOU SHOULD BE TREMBLING IN TERROR!"
"Yeah, yeah." Kai twisted the final brass screw into place, a tiny gold magic circle flashing over the miniature device. "I am Trembling. Totally trembling like a girl after orgasm."
Within five seconds flat, a pair of highly compact, custom-fit earplugs sat in his palm. He shoved them into his ear canals with a satisfied nod, instantly cutting the ambient noise of the forest down to a dull, muffled hum.
"First rule of dealing with a sentient murder-song demon," Kai said, stretching his neck. "Mute the audio."
The demon's jaw dropped. "…What?"
"If you start singing, I literally can't hear you," Kai explained loudly, checking the seal on his right ear. "Your pitch is probably terrible anyway."
The purple fires inside the demon's eye sockets erupted. "HOW DARE—"
Kai held up a single finger. "Shh. You're giving me a headache."
Driven into a frenzy, Lullaby brought a massive fist crashing down on the spot where Kai stood. The earth shattered, but Kai was already gone, reappearing a dozens meters away in a fluid blur.
He cupped his hands around his mouth, shouting over his own earplugs: "Oi! Crusty!"
The demon froze, slowly turning its gargantuan head toward him.
Kai's expression remained entirely bored. "Are you done with the speech, or should I manufacture a giant gag to shove down that hollow face of yours?"
The Lullaby shook, its entire mass trembling with a volatile mixture of outrage and sheer disbelief.
Kai dusted off his trousers, rolled his shoulders, and took a solid stance. "Well? Come on then. If we're doing this, let's wrap it up. I want to get some sleep before sunrise."
Lullaby's subsequent roar split the night air like a jagged saw tearing through steel. The monster swelled with power, a massive, rotating purple magic circle expanding beneath its feet. The ancient sigils inside pulsed like a localized plague.
"DIE, HUMAN!" the demon bellowed, the sound waves flattening the surrounding treeline. "LET THE SONG OF DEATH DEVOUR YOU! YOU THINK BLOCKING YOUR EARS CAN SAVE YOU FROM THE CURSE OF MY MAGIC?"
A violent wave of dark energy exploded outward from the circle—thick, suffocating, and thoroughly corrupt. It swept over the terrain with a wet, rotting hiss. The grass turned to ash instantly, tree roots blackened and curled into dust, and the very air turned heavy and foul.
Kai felt the crushing pressure the moment the shockwave hit him. It wasn't just sound—sound was easily handled by his craft. This was a physical curse, an oily, malevolent ethernano trying to seep through his skin and rot him from the inside out.
He exhaled a calm plume of breath into the cold night. "So it carries a secondary miasma. Good to know."
Steading his stance, he tapped two fingers against his sternum.
"Shadow Monk Arts: Second Skin."
A razor-thin, interlocking armor of shifting, liquid darkness coated his flesh, clinging to him like a sleek exoskeleton. The wave of death magic washed over him a millisecond later, splashing violently against the dark barrier.
And nothing happened. Kai didn't even blink.
Lullaby's glowing eyes went wide. "HOW—"
He never got to finish the question. Kai vanished.
A deep, low-frequency pulse echoed through the dirt where he had just been standing—the signature acoustic pop of a Shadow Step.
In a fraction of a heartbeat, Kai materialized directly beside Lullaby's massive right ankle. His right palm was already extended, glowing with a highly condensed, volatile spiral of kinetic force.
"Shadow Monk Arts: Piercing Palm—Echo Form."
He drove his open palm into the wood-and-smoke leg. The initial strike pierced cleanly through the demon's dense exterior like a hot knife through butter. A split-second later, the secondary kinetic echo detonated violently inside the cavity.
The entire lower limb tore clean off, splintering into thousands of jagged, smoking shards.
Lullaby howled in agony, its balance shattered as its leg gave way. The ground groaned as the titan dropped heavily onto one knee, kicking up massive waves of dirt.
Kai was already scaling the monster. He dashed up the creature's collapsed leg, his body partially dissolving into writhing shadows, gliding upward like a streak of ink.
"Damn you, insect!" Lullaby snarled, swinging a massive hand in a sweeping arc to crush him against its own torso.
Kai flicked his wrists. The heavy cloth wraps binding his forearms snapped free, shooting skyward like harpoons and hooking onto the jagged horn-like protrusions on the demon's face. Using the tension, he swung himself out into a wide arc, narrowly dodging the crushing palm, which smashed into the demon's own knee with a deafening crack.
Using the recoil of the wraps, Kai launched himself forward, his boots connecting squarely with Lullaby's jaw, snapping the massive head backward. Still airborne, he flipped gracefully, landing directly on the demon's broad shoulders. With a sharp flick of his fingers, he redirected the trailing wraps, coiling them tightly around the monster's thick neck.
Kai dropped off the behemoth's back, letting gravity do the work, and yanked the fabric with everything he had.
Cursed wood, dense shadow, and ancient magic strained and snapped. Lullaby's head was violently jerked backward at a grotesque, broken angle. The massive entity toppled over like a collapsing tower, smashing into the earth with a thunderous impact that sent a shockwave through the entire valley.
Lullaby lay cratered in the dirt, stunned and choking on its own fluid rage.
"HOW… HOW IS THIS POSSIBLE?!" it shrieked, its form beginning to destabilize. "YOU ARE A MERE HUMAN! MY SONG IS NO ORDINARY SPELL, IT IS AN IMMORTAL CURSE! IT SHOULD HAVE—"
Kai couldn't actually hear a word of the existential crisis the demon was having, otherwise he would have gladly informed it that his earplugs were fully enchanted.
Sensing the human's complete lack of presence—Kai's magical signature was completely masked, flickering in and out of the shadows like a ghost—the demon panicked. It lashed out wildly, trying to find its bearings. Its remaining leg scrambled for purchase, but a sudden, violent tug from below pinned it to the spot. Kai's wraps had slithered directly out of the demon's own shadow, locking its limb to the earth.
But the demon was ancient, and it fought back with savage desperation. Shifting its massive weight, it grabbed the woven wraps with its bare hands and gave a monstrous, upward heave.
Kai was dragged out of the shadows like a hooked fish, pulled into the open air where he dangled defencelessly. Lullaby reached up with its free hand, its fingers elongating into razor-sharp talons.
"NOW DIE!"
The talons lunged. Kai acted on pure instinct. He flicked his free hand, firing a secondary wrap that anchored onto the incoming wrist. With a precise burst of mana, he severed the line the demon was holding, dropping like a stone just as the talons whistled through the empty space where his chest had been.
The demon's hand struck air, but it instantly spotted the wizard now swinging toward its opposite arm. Not wasting a single frame, the titan whipped its hand downward, intending to paste Kai into the bedrock.
The fist pulverized the earth, but it smashed nothing but dirt.
Kai was already airborne, utilizing the momentum of the swing to launch himself high into the midnight sky. An intricate, deep-violet magic circle bloomed into existence directly behind him.
In his right hand, a weapon materialized. It was a long, blackened combat spear, its surface etched with rushing aerodynamic runes. Embedded just beneath the heavy spearhead was a large, crystalline lacrima glowing with a faint, empty hum. Dark energy spiraled wildly around the haft, merging with his shadow magic until the air around him began to warp from the sheer kinetic pressure.
Kai pulled his arm back, his posture perfect. "Don't move," he called out casually. "This is going to hurt."
Lullaby's jaw split wide open, a blinding, golden radiance gathering in its throat as it channeled every single drop of its remaining death-magic into a singular point.
The blast condensed, then erupted. A massive, destructive beam of pure golden light incinerated the ground below as it shot straight toward the falling wizard.
Kai hurled the spear.
"Kairos Sunviel Original: Dark Singularity!"
The spear tore through the sky with a deafening sonic boom. The dark energy wrapping the weapon created a localized gravitational vacuum, warping the air into a visual spiral. It collided head-on with the golden beam of death—and it didn't slow down.
The empty lacrima at the spearhead flared to life, greedily drinking in the demon's concentrated magic beam, feeding on the destruction, absorbing it until the crystal pulsed like a dying star.
It pierced completely through the golden spell, shattering the beam into harmless particles, and struck Lullaby dead center in its runic core.
A single, deep thud echoed through the valley. A heartbeat of absolute silence.
Then—BOOM!
A catastrophic detonation of pressurized black and gold energy swallowed the entire clearing. Caught in the immediate aerial shockwave and completely out of magic to defend himself, Kai was thrown through the sky like a ragdoll. His ears rang, his vision blurred, and every muscle in his body screamed in protest as he skipped violently across the rough terrain before finally skidding to a halt in a freshly plowed trench of dirt.
He lay there in the quiet, twitching slightly.
"…Ow." His voice was a hoarse, pained whisper. "Why do my own crafts always blow up in my face? I swear… when I get back to civilization… I'm retiring from dark artifact hunts."
Gritting his teeth, he took inventory of his body. Every single injury from his previous encounters had torn wide open. His bandages were shredded, his shirt was reduced to literal fiber, and he felt like his skeleton had been thoroughly processed through a meat grinder.
Is this cosmic karma for lying to Erza and the others? Probably.
He forced his head to turn. In the distance, the giant smoke-demon was entirely motionless. It was charred, smoking, heavily cracked, and rapidly dissolving back into harmless ambient ethernano.
Kai let out a long, ragged sigh of relief. "At least the spear worked. Good thing I liberated that orichalcum model from Erza's spare armory… though I completely burned through my entire back-up lacrima supply to pull that off."
He coughed weakly, staring up at the stars. "And thank my brilliant self for the improvisation. Tinkerer magic to fuse the stolen spear with empty storage crystals, Shadow Monk arts to reinforce the throwing arm… yeah, I'm never doing that again."
With trembling fingers, he fished a small, silver pocket watch from his spatial pouch. The mechanical hands were just crossing 11:58 PM.
"Any… second now," he muttered.
The moment the second hand clicked perfectly into place, a massive, brilliant magic circle materialized directly above his floating body. Intricate clockwork gears turned in perfect unison, and shimmering threads of golden time-magic spiraled downward like a warm cocoon.
Kai didn't panic. Suddenly, his medical supplies began shooting out of his pouch in a neat, organized parade—fresh bandages, soothing salves, wooden splints, and high-grade health potions. They floated around him as if orchestrated by invisible hands. The magic gently lifted him off the cold dirt, suspending him in the air as the automated unseen force began cleaning his wounds, setting his fractured ribs, and applying the medicine with clinical precision.
He let out a blissful groan. "Ah, yes… my absolute masterpiece."
Kairos Sunviel Original Magic: "I Will Do It Eventually."
Hours ago, right at the start of the Lullaby encounter—back when he actually had a healthy pool of magic to spare—he had cast the spell with a specific intent: "I will properly patch my wounds and return to Kunugi town today."
It was a simple task. A chore well within his capabilities. And because he had fed the spell the necessary mana and absolute intent, the magic was bound by an absolute paradox: If he stated he would complete the task today, the magic would fundamentally alter reality to ensure it happened before the day ended.
The final two minutes of the night were still technically "today."
He had intentionally waited out the clock during the fight, knowing that by pushing the deadline to the absolute limit, the spell's notorious randomness would be entirely bypassed. The magic had to trigger right now, or risk breaking its own fundamental law.
Kai snorted, wincing slightly as a golden thread pulled a cracked bone back into alignment. "Ouch—hey, watch the pressure, gently now. See? I told those idiots back at the guild… it's not a useless spell. It's called strategic procrastination."
He closed his eyes, letting the automated magic handle the tedious process of healing and levitation as his body was slowly, comfortably drifted through the night air toward Kunugi. Before he lost consciousness entirely, he cast a lazy shadow wrap out to grab the now-purified, harmless wooden flute resting in the crater.
A small smile played on his lips. "I should probably thank the Eisenwald fools for hijacking the train and wrecking Kunugi station ahead of time. Otherwise, the local station master would have probably had a heart attack seeing a half-dead wizard floating into town on a cloud of bandages."
Above him, the clockwork circle hummed its quiet, rhythmic song. Around him, the cool night air carried him smoothly toward the town lines.
And miles away, completely oblivious, Erza, Natsu, Gray, Lucy, and Happy were pushing their magic vehicles to the absolute limit to reach Oshibana station, entirely unaware that the world-ending threat of the Lullaby had already been dismantled, logged, and solved by a teenager who just wanted to get some sleep.