Rein’s eyes opened slowly.

  His body remained in the same cross-legged posture as before, but everything else had changed. The world was no longer a blank room bathed in pale light—he knew it now, without doubt.

  What he experienced moments ago inside the Mana Realm hadn’t been a dream, or a hallucination, or some grief-born delusion.

  Because the very first thing he saw upon waking… was mana.

  Not the vague shimmer he’d glimpsed during training, nor the distorted blur seen when injured. No—this was clarity. Mana drifted through the room in glittering particles, flowing together like threads of soft, luminous water. They swirled upward in slow spirals toward the ceiling.

  There, carved sigils caught the flow, gathered it, refined it, and exhaled it again as warm illumination that filled the ward.

  Rein breathed out, astonished.

  The fusion between Dr. Rhys Rattana’s mind and the original Rein’s instincts wasn’t complete—far from it—but it was more than enough to let him grasp the phenomenon instantly.

  He was seeing the world through Mana Vision. Truly.

  “Wireless power delivery. Zero wiring. Zero loss.”

  He squinted up at the glowing sigils.

  “If Nikola Tesla could see this, the man would weep.” He couldn’t help but smile.

  The world looked completely different through Mana Vision—more alive, more deliberate, as if every object hid a blueprint waiting to be read.

  Some sigils above him pulsed with faint green light. Healing sigils.

  Through Mana Vision, their function became obvious. They were converting ambient mana into healing mana—slowly, gently, feeding it into his body in a continuous trickle of green motes. Not as effective as Ingrid’s or Master Chloe’s healing spells, but a quiet, steady stream all the same.

  Rein tapped his finger absently on the edge of the bed, a habit carried over from Rhys.

  “…So this is how it works. Mana isn’t ‘magic.’ It’s… instructions.”

  And suddenly, his mind snapped the pieces together like a half-forgotten jigsaw puzzle.

  “Wait—this is basically hacking the laws of physics.”

  He sat up a little straighter, eyes bright.

  “In my old world, physics equations formed the system’s core code… but here, mana itself acts like a low-level programming language.”

  The thought exhilarated him.

  "Mages aren't 'casting magic.' They're writing commands. Or—" he snorted, "—copy-pasting ancient scripts they barely understand. Deprecated code formats dressed up as sacred incantations."

  He could almost hear Liz’s voice teasing him for monologuing again. She used to say he lectured himself more than he lectured other people—which explained why nobody stuck around to listen.

  Rein rubbed his chin.

  “But if someone actually understood the syntax of mana… if they could write instructions directly instead of memorizing canned incantations… that would be true magic.”

  He paused.

  Then huffed a quiet laugh.

  "And in that analogy… Heroes had root access. And the gods? System administrators of the universe. Of course."

  He couldn’t help smiling—quiet, satisfied—with the theory taking shape in his mind.

  “At this rate, learning magic shouldn’t be too hard,” he murmured. “Even if I’m starting from zero all over again.”

  Rein shrugged lightly and hopped down from the bed.

  His movements flowed in perfect sync with his thoughts—smooth, precise, almost effortless.

  His body felt aligned at last, nearly one hundred percent in tune with him.

  As he loosened his shoulders and stretched his arms, Rein couldn’t help recalling the way he had once tried to mimic spellcasting by imitating poses from movies.

  Looking back now… yes, the old Rein laughing at him made perfect sense.

  With Mana Vision active, the truth of this world felt painfully obvious.

  Even someone born in Arath would fail to cast anything beyond a single cantrip—if they’d never once perceived mana. They could train for years, decades even, and still accomplish nothing.

  "It's like asking a blind man to return a tennis serve," he muttered. "Thousands of tries, tens of thousands—he'll never hit one." He almost felt sorry for his past self.

  He continued warming up lightly, feeling power welling inside him, carried by the combat instincts that belonged to the original Rein. Those instincts streamed into his consciousness like a river, merging seamlessly with Rhys’s scientific reasoning.

  After only a short minute of light movement, sweat trickled down his neck. His breathing quickened far faster than it should have.

  He came to a stop, inhaling slowly, deeply.

  Before leaving the Mana Realm, LIZ had warned him—his mana reserves were nearly empty.

  So he activated Mana Vision again, focusing on the ring-shaped Core Mana Circle near his heart.

  The glow was faint.

  Pale.

  Weak—especially compared to the dense mana saturating the healing ward.

  “So when mana drops past a certain point, the body gets exhausted,” he murmured.

  “Meaning physical fatigue is literally tied to mana depletion.”

  He rubbed his chin thoughtfully.

  “The real problem is… I have no idea how much mana counts as ‘almost empty.’ And worse—we have no numerical way to measure it.” He sighed.

  He would have to rely on experience and intuition—and Mana Vision—to gauge it.

  And even that was risky; he still didn’t know exactly how much mana the skill consumed each time he invoked it or whenever he connected to the Mana Realm.

  Thinking of the Mana Realm—and of the fact that it had somehow evolved into LIZ—made him pinch the bridge of his nose.

  “That whole situation is insane. I’ll deal with it when I can reconnect. Maybe the Nackerl executives were right not to trust AI.”

  Shaking his head, he muttered, “This is absurd…”

  A sudden, stabbing pain ripped through his eyes.

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  “—Ah!”

  His hands shot up instinctively to cover them. His body fell back, slumping against the bedside frame as the agony intensified. It was as if a thousand needles were being driven straight into his eye sockets.

  “Is it because I used Mana Vision for too long…?”

  Of course.

  Mana Vision was a Heroic Skill. It demanded mana continuously—and strained the body as well.

  A dangerous combination.

  In a real battle, if he overused it alongside other spells, he might burn through his mana completely without noticing.

  His mind flashed back to the memory of the previous Rein nearly collapsing with mana depletion during the Warlock’s attack.

  If Master Chloe hadn’t arrived in time…

  He wouldn’t have survived.

  Now breathing heavily, Rein analyzed the sensation with more clarity.

  It made sense. A Hero’s skill was not designed for ordinary bodies. The strain, the mana cost—the burden it placed on the eyes—was immense.

  A double-edged sword, exactly as the boy had warned.

  “Oculus Clausus.”

  Let the eyes close.

  The command triggered instantly.

  Mana Vision folded away, and the world faded back to its normal state.

  He blinked repeatedly, tears gathering at the corners of his eyes.

  But the pain receded, slowly, steadily.

  After taking several long breaths to steady his thoughts, he assessed the rest of his condition.

  His muscles trembled with leftover fatigue. Sweat clung to his skin like he’d just finished an intense training session. A mild dizziness pulsed behind his temples—like the onset of a fever.

  “…Yeah. I overdid it. Definitely need to ease off.”

  Fortunately, he was still inside the special healing ward.

  The ambient healing mana continued working in gentle pulses—slow, not as potent as a direct spell from Ingrid or Master Chloe, but steady enough to gradually restore his body.

  Rein exhaled deeply, letting the ward’s light settle over him like a warm mist.

  For the first time since awakening in this world…

  he finally understood why magic felt impossible before

  —and why it didn’t anymore.

  Rein shuffled toward the small washroom, splashing cold water over his face and giving himself the fastest cleanup he could manage. A few minutes later he returned to the room, changed into a fresh set of clothes, and collapsed onto the bed.

  A short rest—that was all he needed. Even an hour or two would help his body and mana stabilize.

  He’d lived in this healing ward for over two weeks now.

  He understood its rhythms.

  With the continuous healing sigils overhead, even a brief sleep usually restored him just enough to think straight.

  Anything was better than the dizziness making the whole room spin.

  Even with his eyes closed, he could feel mana drifting through the air—threads of energy slowly funneling toward the mana ring near his heart with each breath. A single completed mana ring placed him at the proper threshold of a Troposphere-tier Master, but filling it to capacity would take time.

  If he wanted it full… dawn would probably come first.

  Well. I’ve got the whole night, anyway…

  Wrapped in silence—save for the faint hum of the healing array above him and the herbal fragrance that gently soothed the nerves—Rein drifted off within minutes.

  He didn’t stay asleep for long.

  A deep, shuddering boom tore through the silence, strong enough to send a tremor through the floor. Dust sifted down from the ceiling in thin trails.

  Rein’s eyes snapped open.

  “What was that!?”

  For a moment he wondered if he’d misheard it—some half-dream echo—but then he glanced toward the old clock sitting beside his bookshelf.

  Its soft blue-glowing hands pointed clearly at 21:10.

  He had slept for barely thirty minutes.

  Not a dream, then.

  He’d always thought it convenient—almost suspiciously so—that time on Arath followed the same twenty-four-hour cycle as his old world.

  If it didn’t, adapting would have been an absolute nightmare.

  The ceiling rumbled again—louder this time.

  Like a brawl. Or worse.

  If this were still Dr. Rhys Rattana—just a scientist—he would have hidden first and asked questions never.

  But Rein’s heart kicked hard against his ribs, and instead of fear… something sharper surged inside him.

  A warning. A premonition of danger. And yet not a trace of hesitation.

  He checked his body again. The fatigue had faded; the stabbing pain behind his eyes was gone; and the dizzy spell had vanished completely. His mana, while low, was no longer scraping the bottom—maybe ten percent, give or take.

  Still… ten percent wasn’t ideal.

  Then he remembered.

  The potions.

  He jumped off the bed and hurried to the small table. Two bottles sat neatly on top: one labeled Mana Potion, the other Life Potion.

  And inside a small wicker basket were two smaller vials—also blue, but thinner and meant for emergencies.

  The mana potion glowed faintly—transparent blue, swirling like liquid moonlight inside a 250-milliliter glass bottle.

  The life potion shimmered red, radiating a soft luminescence even in the dim room.

  Ingrid had given all of these to him days ago “just in case”; she’d even lectured him on their effects in case his memories didn’t return.

  But at the time, he’d been too absorbed in studying Bratos’s texts to bother.

  Now he was grateful she insisted.

  Rein picked up the mana potion and tilted it back and forth, chewing on his lip.

  Should he drink it now?

  Another violent crash from above shook the room.

  Decision made.

  He popped the cork and chugged it in one go.

  The glowing liquid slid down his throat like cold syrup.

  He finished it in seconds, set the empty bottle down, and wiped his mouth with his sleeve.

  Then stuck out his tongue—now bright blue—and muttered darkly:

  “Ugh… disgusting. Ingrid, you seriously need cocktail lessons…”

  The bitterness lingered, but only for a moment—because the next instant, his eyes widened.

  Mana surged through him, rushing into the mana ring near his heart with the force of a compressed jet.

  “Whoa—this is like injecting nitrous oxide straight into the system… at least a twenty, maybe twenty-five percent boost.”

  The dizziness evaporated. Energy pulsed through his limbs—brisk, sharp, alive.

  He grabbed the remaining potions, gripping them tightly in one hand.

  Whatever was happening above…

  he’d face it head-on.

  But when he glanced at the mirror, Rein grimaced.

  He was still wearing the loose white patient outfit—fine for lying in bed, but wandering the halls at night like this?

  Not a good idea.

  After hesitating a moment and glancing left and right as if someone might scold him, he made a decision.

  He grabbed the black cloak draped over Master Chloe’s chair.

  It looked vaguely like a researcher’s lab coat—familiar in shape, comforting even—but dyed in matte black rather than clinical white.

  And the moment he slipped it over his shoulders, a strange surge of confidence settled through him, tightening his posture.

  He pulled the door open.

  The hallway outside—normally bright enough to sting the eyes—was now lit only by two faint wall lamps, their glow flickering weakly.

  As if the lighting array had been damaged. Or disrupted.

  Rein’s brows knitted. Something was wrong.

  But before he could analyze further, another distant boom echoed through the halls—sharper this time, vibrating through the stone.

  No more thinking. He broke into a run.

  The world blurred around him. Footsteps light. Breathing steady.

  Every movement—every shift of weight—was sharp, efficient, instinctive.

  This was nothing like Dr. Rhys Rattana’s jogging routine back on Earth.

  This was combat movement—low center of gravity, head angled forward, ready to dodge, ready to strike, ready for anything.

  Even his speed bordered on the absurd.

  Closer to an Olympic sprinter than a teenage mage recovering from mana depletion.

  “Wow… a teenager’s body really is cheating.”

  A grin tugged at the corner of his mouth.

  The mind and soul were different, but the instincts of this body were very much alive—honed from years of battle and refined training.

  Even underground, he could hear distant clashes.

  Not just the rumble of impacts—he could distinguish the arcs of spells, the number of collisions, how many shots missed.

  This body is absurd.

  Lamborghini Aventador absurd.

  "Just tapping the throttle and I'm practically airborne," he muttered. Compared to this, the old Rhys was a standard sedan at best.

  The dim corridors of the underground research wing didn’t hinder him in the slightest.

  Earlier that morning, when he’d walked with Ingrid, he had memorized every hallway, every turn—mapping the layout into a neat mental diagram.

  And now he sprinted through it with unerring certainty.

  He ran toward the sound.

  Not out of courage. Not out of curiosity. But because the instincts of this young mage pulled him there—hard and fast—until his heartbeat roared in his ears.

  This glossary defines key magical systems, concepts, and characters introduced or expanded upon in Chapter 11. More entries will be added as the story progresses.

  Heroic Skills

  Mana Vision (Update)

  A Heroic Skill that allows the user to perceive mana in real time—both as ambient particles in the air and as active constructs within objects or spells. Activation allows for advanced analysis of mana flow, spell mechanics, and magical architecture. The skill consumes mana continuously and places immense physical strain on the eyes, making prolonged use dangerous.

  Core Concepts

  Core Mana Circle (Update)

  The internal magical formation near the heart that serves as a conduit and reservoir for mana. Every mage has a Core Mana Circle, and its complexity and capacity determine their magical tier.

  For example, Rein possesses a fully formed Troposphere-tier Core Mana Circle, which allows him to channel a steady flow of mana for combat and analysis. The shape, rotation, and density of the circle affect spellcasting speed, precision, and mana control.

  In moments of stress or exhaustion, this Core Mana Circle can become unstable, resulting in mana depletion or casting failure.

  Mana Depletion (Update)

  The physical and mental exhaustion that results from draining one's mana reserves. Symptoms include dizziness, fatigue, and in severe cases, temporary collapse. Rein experiences this after extended use of Mana Vision.

  Infrastructure-Based Magic

  Auto-Regenerative Inscribed Healing Magic Circles (Update)

  Magically inscribed symbols embedded in the ward ceiling that passively convert ambient mana into healing energy. They continuously channel low-level healing effects to anyone within range, helping patients recover gradually over time.

  Theoretical Magic Concepts

  Mana as a Programming Language

  Rein proposes a theory: mana is not simply a source of energy, but a low-level programming language that interacts with the physical world. Spells are essentially "commands" or "scripts" written in this language, executed via incantation or sigils. This concept redefines mages as magical coders.

  Wireless Mana Transfer

  Observed via healing sigils, this concept mirrors real-world wireless energy delivery. In this case, mana is captured, refined, and projected throughout the room without physical conduits.

  Mana as “Instructions”

  Rein compares mana-based magic to a software environment where mages are "script kiddies" using copied code (spells) without understanding the underlying language. He believes that full mastery requires direct command of mana syntax.

  Hero = Root Access / Gods = System Admins

  A metaphor coined by Rein. Heroes have high-level access to manipulate reality (via Heroic Skills), while deities like Goddess Luminara function as overarching system administrators.

  Magic as Physics Hacking

  Rein postulates that magic in this world is essentially the manipulation of physical laws through mana “code,” likening it to hacking reality.

  Items & Artifacts

  Mana Potion

  A concentrated, glowing liquid that rapidly restores a portion of the caster's mana reserves. Rein notes that one bottle replenishes roughly 20–25% of his mana circuit, though effects may vary by individual. Side effects include bitter taste and slight overstimulation.

  Life Potion

  A red, luminescent potion designed to restore physical health, especially in emergencies. Kept on hand for high-risk scenarios.

  Power is no longer just something to learn; it is something to interpret.

  would you be ready for what it shows you?

  See you in the next chapter.

  —Re:Naissance