Reincarnated as The Greatest Scientist in Another World

A week had passed since Zuko Hearthfilia, the Seventh Prince of the Holy Stone Kingdom, had brought wagons of food and clothes to the Null settlement on the edge of the capital's reach. In that short span, rumors seeped through every corridor of the castle, coiling like venomous serpents through marble halls and golden chambers.

Beneath the towering pillars of the Council Hall, mages and noblemen gathered — robes of sapphire and gold whispering as they shifted in their seats. Their voices hissed in harsh undertones, thick with fear and contempt. The semicircle of seats before the High Throne of King Barnabas Hearthfilia trembled under the weight of centuries-old tradition now bruised by the reckless kindness of a single wayward prince.

"He defies the natural order!" Chancellor Ruden barked, slamming his staff against the marble floor so hard that sparks of blue mana flared along its runes. His thin lips twisted in disgust. "He feeds cattle! If the Nulls think they deserve more, what next? Weapons? Land? A seat among us?"

Murmurs rose and rippled like an angry tide. On the High Throne, King Barnabas sat unmoving, his jeweled crown weighing heavy on his silver hair. Deep lines bracketed his eyes — decades of rule, secrets, and sacrifices carved into flesh. He did not wish to punish his youngest son, yet the snarling pack of nobles and mage-councilors left him no escape.

One advisor leaned close, his whisper soft as silk and sharp as a blade. "Your Majesty, the people watch. If you show weakness before the Nulls, faith in the Hearthfilia line will crack."

Barnabas closed his eyes. Zuko's fierce gaze flashed through the darkness — his seventh son, the only one who spoke of peasants as people, who spat in the face of gilded rules. The king's voice broke the murmurs like dry timber snapping in winter frost.

"Ready the knights," Barnabas breathed. "Bring the boy home. Bring discipline back to my house."

---

Far from marble pillars and silken cloaks, beneath thatched roofs and bamboo walls, Ain knelt on sunbaked dirt, his fingers black with soot and grease. Around him lay scraps of copper, battered iron, shards of glass, and mirror fragments arranged in a rough, desperate circle. His thin hands trembled as he twisted wires, binding a metal plate to a cracked pane of salvaged glass — once part of a noble's shattered window.

"Are you sure this will work?" Zuko asked, crouched beside him. The cool night breeze did nothing to stop sweat dripping from his brow. His cloak, once regal velvet, was now plain brown to hide the crest that had once opened every door.

Ain didn't lift his eyes. Hollowed by sleepless nights, they burned with a feverish spark — a hunger for possibility that no hunger for bread could match. "It has to," he murmured. "The sun gives more than warmth. It feeds the wire. The wire feeds the light."

Zuko raised a brow, the corner of his mouth quirking. "I've seen mages summon light with a snap of their fingers. This—" he gestured at the heap of junk — "looks more like a broken pot."

Ain paused. Then, thin and ghostly on cracked lips, came a smile. "Then watch a Null build what mages can't even imagine."

For days, the settlement had watched him drag home scraps, polish shards, and dig through garbage pits near the city's walls. Curious children peeked through broken doorways, whispering as this sharp-eyed boy scribbled notes in a battered notebook no one else could read.

And tonight — tonight, they gathered.

Dozens of Nulls formed a loose circle around Ain's crude contraption. Mothers clutched their children closer. Old men with clouded eyes squinted through the dark, wondering if this was just another promise doomed to break.

Ain wiped his brow, then stood. Zuko stepped back, arms crossed, amusement flickering in his eyes. "All right, genius — light it up."

Ain took a breath, heavy as thunder in his ribs. Five… four… three… two—

A faint click. A low hum — like an insect waking in the dark. The bulb — a cracked glass sphere stuffed with scavenged copper and the last drops of melted lead — flickered once. Then, as if the sun itself bent low to kiss the dirt, it glowed.

A warm yellow light spilled across the circle — grime and scars softening in its gentle reach.

A collective gasp rose, then silence cracked open — and cheers poured out. Broken voices shouting a single name: "Ain! Ain! Ain!"

Ain's mother sank to her knees, tears streaming down sunken cheeks. A small boy reached out, trembling fingers grazing the light that needed no mage's spell.

Ain turned to Zuko — the prince who had hauled wood, who carried planks, who scavenged glass with him in the dark.

He raised a hand for quiet. The crowd hushed — every heartbeat straining for the next word.

"This light," Ain said, voice hoarse but strong, "is not mine alone. It lives because Prince Zuko brought the wire. The glass. The hope."

The crowd turned. Dozens of eyes — once dull with hunger — now burned bright with something raw and fragile.

"Zuko! Zuko!" someone shouted. The name caught like fire in dry grass. "Zuko! Zuko! Zuko!"

Zuko — who always found words to tame a room — found none. For the first time in years, he looked small. Not a prince, not a Hearthfilia — just a man who remembered that people were people.

---

That night, under a sky scattered with stars and Ain's single flickering bulb, the Nulls slept with full bellies, warm blankets, and dreams they'd never dared speak aloud. Ain drifted to sleep beside Zuko, the battered notebook clutched tight to his chest as the new light hummed above.

At dawn, Zuko woke to find Ain gone.

A distant boom split the morning stillness.

Heart pounding, Zuko burst from the hut, bare feet thudding against the dusty earth. Smoke rose from a clearing behind the settlement. He ran — past wide-eyed Nulls, broken fences, and scrap piles — until he saw Ain kneeling in the dirt, thin arms braced around a long iron tube.

Zuko skidded to a halt. "What the hell is that?"

Ain glanced back, soot smeared on his cheek but eyes blazing bright. "A weapon."

He hefted the tube — an awkward, brutal thing of iron, rough wood, and tiny copper runes hammered near the breech.

"I call it the Null Spark Rifle," Ain said, wiping sweat from his brow. "I found ore in the ravines — strange stone that hums with mana. If you crush it, shape it, strike it — it explodes."

Zuko crouched low, eyes flicking over the rough barrel. "That's… that's a magic stone. Mages use them for barriers and rituals. You put it in that?"

Ain nodded, voice steady. "When the stone explodes, it forces a piece of metal — a bullet — forward. Fast enough to punch through armor. Maybe even a mage's shield."

Zuko let out a low whistle, brushing the barrel with cautious fingers. "You're insane."

Ain just grinned — thin, hungry, sharper than any noble's blade. "If they won't give us magic, we'll build our own."

But fate never waits for permission.

At the edge of the path, shapes shimmered in the morning haze — white cloaks, armor gleaming. A dozen knights stepped forward, runed wands at their hips. At their head stood an older man with a deep scar across his cheek. He raised a gauntleted hand.

"Prince Zuko Hearthfilia," he called, voice cold as grave dirt. "By the king's decree, you stand accused of treason against the crown."

The Nulls froze. Mothers clutched children. The old shrank back.

Zuko stepped forward, jaw set. "If you want me, take me. But leave them out of this."

The knight's eyes narrowed. "The king's word is law. The Nulls will be detained. They will be relocated to the mines until your betrayal is judged."

Ain's fingers clenched tighter around the rifle. The light, the bread, the warmth — all of it, threatened again.

"No," Zuko snarled, mana crackling to life on his palms. Blue fire licked his fingertips.

A knight lunged forward — wand raised — but Zuko was faster. He cut the air with a burst of wind, slamming the man to the dirt. Another charged, rune-blade flashing, but Zuko twisted away, lightning bursting from his knuckles.

For a moment, Ain watched — frozen — as the outcast prince fought trained battle-mages like a storm made flesh.

But there were too many.

Ain raised the rifle. His chest heaved. The metal trembled against his bony shoulder.

The knight commander turned, blade leveled at a cowering woman — Ain's mother.

"Seize them all—"

A crack split the dawn. A burst of light. The rifle slammed back against Ain's shoulder.

The commander's head snapped back — a spray of red and a dying flash of blue mana.

Silence.

Then Ain's voice — ragged, savage, pulled from every bruise, every broken promise the Nulls had ever swallowed.

"Nulls will never kneel again!"

And as the sun broke over the rooftops, a rebellion rose with it.