The lingering breeze drifting down through the northern ridge carried away the last traces of ozone, leaving behind the sharp, heavy smell of burnt pine resin and flash-vaporized copper. A few charred leaves tumbled across the clearing as Kai stretched his arms high above his head, his spine popping in a series of dull, satisfying cracks.
Lullaby had done an excellent job repairing his physical injuries, but his internal ethernano reserves were still nearly depleted after running Overdrive. Faint wisps of heat escaped from the black runic markings tracing his forearms, dissipating uselessly into the afternoon air. His flesh had healed, but his energy levels remained entirely drained.
"Ugh. The physical recovery phase is always such a drag," Kai muttered, slumping back against a fallen oak log with an exhausted exhale.
He shoved his hand into his tiny leather hip pouch, his arm sinking past the wrist, then the elbow, disappearing almost to the shoulder inside the enchanted pocket dimension. Metal clinked, a spring snapped, and something deep inside the pouch made a small, offended mechanical whirring noise.
Kai rummaged around for another moment before pulling out two chilled juice boxes, complete with tiny straw wrappers attached to their sides. Without a word, he tossed one across the ten-foot gap.
Rei caught it effortlessly with his left hand. The contrast was absurd: a battered, blood-splattered swordsman standing in the middle of a scorched clearing, his coat torn and his face covered in ash, holding a brightly colored juice box decorated with smiling cartoon fruit.
Rei stared down at the pastel container, his brow furrowing as he looked up at Kai. "What exactly am I supposed to do with this?"
"It's an ancient medicinal elixir," Kai replied smoothly, tearing open his straw wrapper with practiced ease. "Passed down through generations of highly advanced civilisations to cure the weary soul. Or, you know... standard fruit juice."
"I know what juice is," Rei said, his voice flat as he inspected the foil seal. "I am asking why you are offering it to me in the middle of a ruined forest."
"Because you're standing there looking like a breeze could knock you over," Kai said, jamming his straw through the foil tab and taking a long, greedy gulp.
The cold liquid soothed his sore throat, relieving some of the lingering tension in his shoulders. "Drink up, man. Lullaby patched your torn flesh and cracked bones, but your magic reserves are completely spent. Your body's running on pure stubbornness right now."
Rei glanced down at his right wrist and slowly rotated it. The dislocated joint had been restored and the terrible swelling was gone; a dull ache remained beneath the skin, but it was nothing compared to the blinding pain he'd experienced during their fight. "So the artifact doesn't provide a complete recovery."
"It repairs structural damage, which isn't the same as restoring your stamina," Kai explained with a casual shrug. "If I tuned the flute to replenish ethernano and clear muscle fatigue on top of knitting flesh, the power draw would skyrocket. Depending on the local atmospheric density, it could drain the surrounding air just to finish one session. Medical magic and energy restoration operate on completely different principles—you can't fix exhaustion with a simple cellular patch."
Rei studied the juice box for another moment before pushing the straw through its seal and taking a cautious sip.
Kai watched him with a smirk. "See? No poison. You survived the big scary fruit box."
"I was checking the seal, not looking for poison," Rei replied dryly, lowering the box after a short drink. "Do you ever find yourself at a loss for words?"
"Only when I'm fast asleep," Kai drawled, leaning his head back against the bark. "And even then, my subconscious usually keeps the conversation going."
Rei chose to ignore the comment, finishing the rest of the juice in silence. For several seconds, the two remained quiet while the breeze rustled through the damaged trees, carrying the sharp scent of scorched earth between them.
Eventually, the swordsman broke the quiet. "I am still trying to understand how you managed to invert a Zeref-era mass-murder weapon into a recovery instrument. Altering the core resonance of a cursed object like Lullaby should have destroyed its internal casing."
Kai raised an eyebrow, adjusting his slouch. "I've modified plenty of questionable artifacts, but Lullaby was actually pretty straightforward. Once you strip out the soul-eating feedback loop and invert the acoustic conversion channels, it's just a simple process."
"And your physical capabilities have changed since we last met in the subterranean complex," Rei continued, his crimson eyes narrowing slightly as he observed the spatial mage. "Your movement, your reaction timing, even the way you handled your spatial displacement—you were far more precise today than when we fought down in the ruins."
Kai gave him a flat, unbothered look. "What makes you think you saw my actual limit back then?"
When Rei's brow furrowed, Kai scoffed softly. "I'm not going to unleash my full operational output inside an unstable subterranean ruin just to settle a point. My priority back then was extracting a trapped research team and keeping thirty tons of solid bedrock from caving in on our heads. If I'd started throwing around high level spells in those tunnels, we would have been buried alive."
Rei considered the explanation before offering a concise nod. "That is a valid point. I refrained from drawing my blade's full power for the exact same reason. The structural integrity of the ceiling was already compromised."
"Look at us, acting like responsible professionals," Kai smirked, resting his hands behind his neck. "Though, if we're being honest, I have integrated a few new upgrades into my system since that mission."
Rei waited for him to elaborate, but Kai simply closed his eyes, settling into a relaxed posture against the log. A long moment of quiet passed.
"Are you planning to elaborate on those upgrades?" Rei asked, his patience wearing thin.
Kai didn't open his eyes. "Not particularly. I'm running low on energy, and explaining my research takes effort."
"That has little to do with answering a direct question," Rei noted flatly.
"It has everything to do with it," Kai murmured, folding his arms. "Besides, it's late afternoon. That's prime napping time in my schedule."
Rei stared at the slouched mage, realizing that pressing him for trade secrets was a waste of breath. Deciding to redirect the conversation before Kai actually fell asleep, the swordsman stepped forward onto his healed leg.
"Let us move on to business," Rei said, his tone sharpening. "As per our arrangement, I demonstrated the parameters of my weapon during our bout. You promised to show me the Kaldor artifact in return."
Kai kept his eyes closed, raising a lazy hand to point a thumb straight at his own chest. "You're looking right at it."
Rei paused, his brow furrowing in confusion. "Explain what you mean."
Kai opened one golden eye, offering a lazy half-grin. "I said you're looking at it." He gestured toward his bare forearms and chest, where intricate black runic bands were etched into his skin. The dark markings resembled permanent tattoos, but their mathematical geometry was far too precise to have been applied with a needle.
Rei stepped closer, his crimson eyes tracing the lines. Memory stirred as he recalled the ancient relief carvings and conduit channels lining the subterranean walls of Kaldor. The geometric angles matched the patterns on Kai's body with absolute precision.
"These markings," Rei murmured, his stoic demeanor cracking slightly. "They mirror the primary conduits from the first central chamber."
Kai's smirk widened as he tapped his collarbone. "The artifact you came searching for isn't sitting in a chest somewhere. Its primary runic matrix has been integrated directly into my nervous system."
"That should be impossible," Rei said, staring at the markings in genuine disbelief. "An ancient structural artifact cannot simply be absorbed into a human body without tearing the host's ethernano pathways apart."
"It takes a bit of fine-tuning," Kai replied, sitting up as his usual laziness gave way to the faint enthusiasm he reserved for complex engineering. "Kaldor wasn't a normal city built around a power source. The entire settlement was designed as one massive, self-sustaining magical system. The walls, foundations, corridors, and conduits formed a single closed-loop framework meant to capture ambient energy, refine it, and recirculate it without wasting a single drop."
He picked up a small twig from the grass and began tracing rough geometric lines in the dirt. "Think of the city as a massive artificial nervous system. Every corridor carried energy, while the central core coordinated the entire flow. But after centuries without maintenance, the original core deteriorated. It became unstable, drawing in more energy than the channels could regulate."
Flicking the twig away, Kai tapped his forearm. "If I had tried to leave the original core running, it would have eventually overloaded and consumed everything around it. So I salvaged the primary runic matrix, stabilized the core's operating framework, and mapped the surviving architecture straight into my own body. The old core is long gone, but I kept the technical schematics locked away in my office."
Rei looked down at the dark lines tracing Kai's skin, processing the scale of what had been done. "And you wired that entire city-wide system directly into your personal magic origin?"
"That's the simplified version, yeah," Kai said easily.
"What was the procedure for stabilizing such a high-density matrix during integration?" Rei pressed.
Kai offered a pleasant, disarming smile—the exact expression that signaled a hard boundary. "That information is strictly proprietary, my friend."
"Proprietary?" Rei repeated, his eye twitching slightly.
"Meaning it's mine, and I'm not sharing the user manual," Kai chuckled, rising from the log to roll his shoulders. He had no intention of detailing how he had integrated Kaldor's architecture; the process had been far too dangerous and deeply dependent on his Tinkerer Arts to discuss with a wandering swordsman.
Instead, Kai turned his attention toward the silver-filigreed hilt resting at Rei's waist, his golden eyes lighting up. "Now then. It's your turn to spill the details on that sword."
Rei immediately shifted his stance, resting his palm over the hilt. "I have already fulfilled my part of the agreement by demonstrating its combat parameters."
"You showed me what it does in a fight, not how it works," Kai countered, stepping closer with a grin. "Come on, don't hold out on me now. You owe me the history behind that blade."
Rei stayed silent for a long moment, weighing the request against their prior exchange, before letting out a quiet sigh. His crimson eyes searched Kai's face.
"Tell me, Kairos... do you believe in Dragon Historia?" Rei asked unexpectedly, his tone quiet and measured. "The ancient accounts detailing a world ruled entirely by dragons—a period most modern scholars dismiss as mere fable and folk mythology?"
Kai raised an eyebrow, a faint, knowing smirk touching his lips. He thought of Natsu's unyielding searches for Igneel, the ancient ruins he had personally excavated across the continent, and the residual dragon ethernano signatures he had analyzed in sealed subterranean vaults.
"I don't just 'believe' in it like a fairytale, man," Kai said smoothly, leaning his hip against the log. "I've dug through enough four-hundred-year-old strata and analyzed enough anomalous magical residues to know that giant lizards ruling the continent wasn't a myth. It was historical fact. Now stop stalling."
Rei gave a single, satisfied nod. "Then you will understand the purpose of this weapon. Like the Kaldor framework, this blade is an artifact from that forgotten era. It belongs to an ancient class of specialized armaments known as Dragon Blood."
Kai's eyebrows rose. "Dragon Blood? That's a bit dramatic, even for ancient smiths."
"During the dragon era, humanity possessed almost no effective means of harming dragons," Rei explained, his tone growing solemn as he looked off toward the ridge. "Their hides were extraordinarily dense, and their natural magical resistance caused standard elemental spells to dissipate harmlessly off their scales. Before Dragon Slayer Magic became a recognized discipline, ancient weapon-smiths attempted to forge gear that could bypass those natural defenses."
Kai leaned in, his posture shifting into acute focus. "So the sword isn't just sharp—it has a specific functional mechanism built into the metal."
"Correct," Rei continued. "The blade was forged with angled geometry intended to slip between dragon scales, but its true function lies within the magic embedded in the hilt and guard. It acts as an internal conversion system, shifting the wielder's ethernano into distinct elemental outputs while altering their magical signatures so they don't dissipate upon contact."
Kai raised a hand to interrupt, squinting at the hilt. "Wait a second. You're telling me that tiny hilt houses a full-spectrum conversion array, a signature modifier, and a stabilization loop, all packed into a single handheld weapon?"
"Yes," Rei replied flatly. "Though as I mentioned during our bout, the design was ultimately considered a failure."
"Because the processing speed is garbage," Kai deduced immediately, his mind mapping out the structural bottleneck. "An array that complex crammed into a portable frame means the elemental conversion takes too long to tune, loses energy during translation, and risks crashing the internal pathways if you try to switch modes mid-fight. How long does a full calibration cycle take?"
"Several seconds, depending on the output required," Rei admitted.
Kai let out a low whistle. "Several seconds? In a fight against a dragon? That's not just a flaw; that's a death sentence. Imagine taking the time to charge an anti-scale strike, only for the target to incinerate you before your hilt finishes reading the frequency."
Rei gave him a dry look. "The smiths who designed it were well aware of the limitation."
"I'm not criticizing their ambition," Kai clarified, stepping closer to inspect the scabbard. "The concept is brilliant. The execution was just limited by the processing hardware of their time."
Kai folded his arms, his golden eyes locking onto the silver hilt with sharp mathematical precision. "And let's be real here... there is zero chance an ancient smithing collective developed an entire functional framework like this just to put it into a single sword. A trial run maybe, but no engineer stops at one prototype. This can't be the only weapon made with this system."
Rei looked at him with a trace of genuine respect in his dark eyes. "You deduce quickly. You are correct. Dragon Blood was not the designation for a single blade. It was the name of an entire series of anti-dragon weapons created during that era—including heavy broadswords, long-range spears, tower shields, and specialized weapon lacrima cores."
As Rei spoke, the lazy slouch vanished from Kai's posture entirely. His golden eyes sharpened, lighting up with the intense, hyper-focused energy of a researcher who had just been told an entire repository of forgotten military technology was waiting to be uncovered.
"An entire series of anti-dragon artifacts?" Kai whispered, a wide, delighted grin spreading across his face as he rubbed his hands together. "Different weapon layouts, different conversion arrays, potentially different solutions to the calibration delay... That is incredible."
"Regardless of its history, do not touch the blade," Rei warned, his grip tightening on the pommel as he caught the manic glint in Kai's eye.
"I just want a closer look at the guard layout," Kai argued smoothly. "I have great hand-eye coordination, I promise."
"Your coordination is not the issue; your complete lack of personal boundaries is," Rei snapped.
Before the swordsman could take a step back, Kai's fingers flicked through the air. A minute ripple of displaced space brushed past Rei's elbow, accompanied by a faint metallic shhhk as the silver blade slid effortlessly out of its sheath.
Rei felt the weight leave his belt. He looked down at his empty scabbard, then slowly raised his head to find Kai standing five feet away, turning the silver sword over in his hands under the sunlight like a collector evaluating a market find.
"How did you even clear the safety catch?" Rei asked, his voice dropping into a dangerous, low register.
"Simple sleight of hand," Kai murmured, completely ignoring the dark aura radiating from the swordsman. "Man... the craftsmanship on this guard is insane. The magical array density inside the crossguard geometry is absurdly tight."
Kai brought the blade closer to his face, his golden eyes narrowing as he tried to trace the internal etchings beneath the silver polish.
The inner layers of the steel seemed to overlap in complex, three-dimensional patterns, refracting the light like iridescent oil on water. Microscopic runic lattices were embedded deep within the metal, linked through sub-surface channels far too intricate to distinguish with the naked eye.
Kai's playful expression gradually faded into a scowl. Dammit.
He rotated the hilt, trying to track the flow of energy through the guard, but the internal pathways blurred into a chaotic mesh. He could use Create to construct devices he understood and Dismantle to break down active spell matrices, but neither ability allowed him to read a passive, multi-layered blueprint hidden deep inside an unfamiliar artifact.
This is the fifth time I've run into this exact wall, Kai thought, his frustration mounting. I can't analyze complex ancient hardware in the field because my eyes can't resolve three-dimensional micro-inscriptions without lab equipment.
A sharp realization took hold in his mind. He needed to develop a dedicated diagnostic command within his Tinkerer Arts—a function that could project a scanning field through his vision to map internal pathways, read sub-surface runic arrays, and translate them directly into usable technical schematics.
Scan, he named the concept internally. Simple, direct, and essential for his future work.
"Hand the weapon back immediately," Rei ordered, stepping forward with his palm extended, his cold composure completely replaced by sharp agitation.
Kai offered him a bright, disarming smile. "Can I hold onto it for just four hours? I'll take it to my laboratory, open up the hilt casing, map the internal wiring, and hand it right back."
"You are not disassembling my blade," Rei said, lunging forward to grab the hilt.
Kai glided backward using a micro-spatial displacement, leaving a faint afterimage in the grass while keeping the sword just beyond the swordsman's reach. "Easy there! You're going to make me drop it!"
"Then stop dodging and hand it over!" Rei growled.
As Kai prepared to shift away again, Rei's boot slammed into the packed dirt with a heavy, booming thud. A wave of crushed gravel exploded outward as high-density physical reinforcement magic surged through the swordsman's legs and torso, compressing his movement into a terrifying burst of speed.
The distance between them vanished in an instant. Before Kai could initiate another spatial shift, Rei closed the gap, caught the Director in a firm, precise headlock, and clamped his free hand tightly around Kai's wrist to immobilize the sword arm.
Caught completely off guard by the sheer physical acceleration, Kai stood trapped in the hold. But as he felt the intense physical pressure pulsing through Rei's reinforced muscles, his golden eyes lit up with genuine interest. "Well, look at that."
Rei glared down at the side of his head, his grip unyielding. "What?"
"Physical reinforcement magic," Kai chuckled, testing the hold with a subtle push. "That's a clean acceleration curve. You do have something other than this magical sword."
Rei stared at him in utter disbelief. "Are you truly analyzing my magic while being held in a restraint?"
"You're holding me in a headlock, not trying to take my head off," Kai pointed out playfully. "There's a big difference."
"Release the sword," Rei demanded.
"Fair enough," Kai said, opening his fingers.
The silver blade slipped from his grip, and Rei caught the hilt mid-air, releasing the headlock and stepping back five paces to slide the weapon securely back into its scabbard with a sharp clack.
Kai casually rolled his shoulders, popping his neck as if he'd just finished a light stretch. "See? No damage done."
"You took a personal belonging without consent," Rei said, checking the scabbard's locking mechanism twice before glaring back at him.
"And I learned something valuable about your personal boundaries," Kai replied smoothly, holding up a single finger. "Mainly that your personal space ends about three inches from your sword belt."
Rei pressed two fingers against his temple, letting out a long, deep, utterly exhausted sigh. "I am beginning to deeply regret initiating this conversation."
"For the record," Kai added, gesturing toward the hilt, "I couldn't have copied the array out here anyway. The internal markings are far too dense for the naked eye. I'd need specialized optical gear just to read the primary index."
Rei paused, looking at him with mild surprise. "You possess equipment capable of reading sub-surface magical arrays?"
"Not yet," Kai admitted, throwing his head back with a loud groan. "Which is why I really need to finish developing a proper scanning command. Being blind to micro-runes is getting ridiculous."
"Regardless of your research needs, I expect you to refrain from touching my equipment in the future," Rei said, adjusting his coat.
Kai immediately brightened, offering a bright, utterly hypocritical grin. "Completely agree, my friend. I absolutely hate it when people touch my stuff without asking."
A vein twitched near Rei's temple, but he forced himself to stay calm and drop the subject.
"Kairos," Rei said slowly, taking a cautious step back as he watched the unhinged, predatory excitement taking over the Director's face. "Tell me you are not planning to seek out the rest of those Dragon Blood weapons."
"Seeking them out? Don't be silly," Kai said, looking genuinely offended before his grin widened into something truly terrifying. "I'm going to locate them, study them, and tear their internal matrices apart. Collectors put artifacts behind glass, my friend. Researchers take them out of the box."
Rei slowly covered his face with one hand, letting out another long, heavy sigh. He had come to the forest seeking answers about the Kaldor ruin, only to discover that the ancient city had been integrated into the spatial mage standing before him, that Kai was actively working on new diagnostic magic, and that he had just handed an unhinged engineering genius a fresh target list of ancient military hardware.
"...I should have kept the details of that project to myself," Rei muttered under his breath.
Kai clapped him firmly on the shoulder, laughing as he turned toward the city path. "Don't be like that! You've just made a massive contribution to the future of magical science. Now, where did you say the nearest Dragon Blood site was located?"
"I didn't," Rei replied flatly, marching past him toward Crocus.
"Right, right, keeping it dramatic," Kai chuckled, keeping pace right alongside him. "Well, you can start giving me the coordinates on the walk back."