The underground training hall smelled of sweat, stone, and the faint metallic tang of worn steel. Tokito Tadano adjusted his grip on his practice sword, feeling the familiar weight settle into his palm like an old friend. Across from him, his opponent—a boy two years his senior named Kaito—circled warily, blade held in a textbook-perfect guard position.
"Come on, Kaito!" someone shouted from the gathered crowd. "You can take him!"
Tadano didn't let the noise distract him. His dark eyes tracked every subtle shift in Kaito's stance, every micro-adjustment of his feet on the packed earth floor. The underground had taught him patience. Sixteen years of living in tunnels and carved-out chambers beneath a conquered world had a way of teaching everyone patience.
Kaito lunged.
The strike was fast—faster than most could manage—but Tadano had already seen it coming in the tension of Kaito's shoulders. He sidestepped, his blade flowing up in a smooth arc that caught his opponent's sword and redirected it harmlessly past his body. Before Kaito could recover, Tadano's practice blade was pressed gently against his throat.
"Yield," Tadano said quietly.
Kaito's jaw clenched, but he dropped his sword. "Yield."
The small crowd erupted in mixed cheers and groans. Tadano stepped back, offering his hand to help Kaito up. The older boy took it, though his expression was sour.
"How do you do that?" Kaito muttered. "You don't even use magic. No enhancement, no reinforcement, nothing."
"Because I can't," Tadano replied simply, releasing his hand. "So I learned to be better without it."
"Learned to be boring, you mean!"
The new voice cut through the dispersing crowd like a whip crack. Tadano didn't need to turn around to know who it was—he could practically feel the heat radiating from behind him before she even spoke.
Hinoka Vivi stood at the entrance to the training hall, one hand on her hip, the other casually wreathed in flickering orange flames that danced between her fingers like playful serpents. Her wild auburn hair was pulled back in a messy ponytail, and her amber eyes gleamed with that familiar competitive fire that had gotten them both into trouble more times than he could count.
"Vivi," Tadano sighed. "I'm in the middle of—"
"In the middle of putting everyone to sleep with your 'proper swordsmanship,'" she said, making exaggerated air quotes with her free hand. The flames on her other hand flared brighter. "Come on, brother. It's our birthday. Fight someone who'll make it interesting."
"You mean you."
"Obviously me."
A ripple of excitement went through the remaining onlookers. Tadano saw Kaito back away quickly, suddenly very interested in being somewhere else. Smart man. Sparring with Vivi was less a training exercise and more a test of survival instincts.
"Vivi, you know the rules," Tadano said, even as he shifted his stance. "Blade work only in the training hall. No magic."
His sister's grin was absolutely feral. "Aw, but where's the fun in that?"
"The fun is in not burning down one of our few training spaces."
"You're no fun, Tadano."
But she drew her own practice sword anyway, letting the flames die down to embers that still glowed faintly beneath her skin. Tadano could see the magic there, always simmering just below the surface, waiting to explode outward. Vivi had been born with fire in her blood—literally. The village elders said she'd been warm to the touch even as an infant, even in the cold depths of their underground sanctuary.
Meanwhile, Tadano had been born with... nothing. No magic. No spark. No gift.
Just a sword and the determination to be better than everyone who did have magic.
They circled each other slowly. Unlike with Kaito, Tadano couldn't predict Vivi's movements. She fought like her element—wild, unpredictable, explosive. She'd break form in a heartbeat if it meant landing a hit, sacrifice defense for a reckless offense, and absolutely did not care about the "proper way" to do anything.
She attacked first, naturally.
Her blade came in high and wild, with too much force and not enough control. Tadano caught it easily, redirecting—
And then she headbutted him.
"Ow!" Tadano stumbled back, stars exploding across his vision. "That's not swordsmanship!"
"You said no magic!" Vivi called back cheerfully. "Didn't say anything about headbutts!"
She pressed the advantage, raining down strikes that had more enthusiasm than technique. Tadano parried desperately, his head still ringing, trying to find an opening. But Vivi's sheer aggressive energy was overwhelming, pushing him back step by step toward the wall.
The crowd was loving it.
Then Tadano saw it—she over-extended on a downward strike, her balance shifting too far forward. He sidestepped, brought his blade up, and—
A burst of flame exploded in his face.
Not a fireball. Not even a real attack. Just a flash of heat and light that made him flinch, blinding him for a crucial half-second. When his vision cleared, Vivi's practice blade was pressed against his chest, right over his heart.
"Yield, dear brother," she said sweetly.
The training hall had gone dead silent.
Tadano looked down at the blade, then up at his sister's triumphant grin, then at the fading embers still flickering around her free hand.
"You cheated," he said flatly.
"I won," she corrected.
"You broke the no-magic rule."
"I bent it slightly."
"Vivi—"
"Oh, don't be such a sore loser!" She lowered her blade and punched his shoulder affectionately. "Besides, it's our birthday. I'm allowed to break some rules on my birthday."
"You break rules every day."
"And today I'm allowed to!"
Despite himself, Tadano felt his lips twitch into a reluctant smile. He couldn't stay mad at her. He never could. They'd spent sixteen years in these tunnels together, training together, growing together, living in the shadows of a conquered world. She was frustrating and reckless and absolutely refused to follow any rule she deemed "boring."
She was also the only person who'd ever beaten him in a sword fight.
"Happy birthday, Vivi," he said quietly.
Her grin softened into something more genuine. "Happy birthday, Tadano."
The moment was broken by a new voice, older and stern.
"Hinoka Vivi. Breaking training hall rules again, I see."
Both twins turned to see Master Renjiro standing at the entrance, his weathered face creased in disapproval. The old swordmaster had been the one to train them both, though he'd always said Vivi gave him more gray hairs than all his other students combined.
"It was just a tiny flame," Vivi protested. "Barely even magic, really. More like... aggressive hand-warming."
"Rules exist for a reason, girl."
"Rules exist to be boring, old man."
Tadano saw Renjiro's eye twitch. He stepped forward quickly before this escalated. "Master Renjiro, it was just a birthday spar. No harm done."
The old man's stern expression softened slightly as he looked at them both. "Sixteen years old today," he said quietly. "Hard to believe. Seems like just yesterday you were both barely tall enough to hold wooden practice swords."
Something in his tone made Tadano pause. There was a weight there, a sadness beneath the words.
"Master?" Tadano asked.
Renjiro shook his head. "Your parents would be proud of you both. That's all." He cleared his throat gruffly. "Now clear out, all of you. Evening meal is starting soon, and the Council wants to see the birthday twins afterward."
The crowd dispersed quickly at the mention of the Council. Tadano and Vivi exchanged glances. The Council rarely called for anyone unless it was important—or unless someone was in trouble.
Given Vivi's track record, it was probably the latter.
As they walked through the tunnels toward their family quarters to wash up, Vivi was uncharacteristically quiet. The passages were carved from solid stone, reinforced with runic inscriptions that glowed with a faint blue light. Earth mages had shaped these halls over sixteen years, creating a warren of chambers and corridors that housed nearly three thousand people—all that remained of their city after the Darks had come.
"Do you ever wonder what it's like up there?" Vivi asked suddenly.
Tadano glanced at her. "The surface?"
"Yeah." She trailed her fingers along the stone wall as they walked. "Real sunlight. Open sky. Space to actually move without bumping into rock walls every five seconds."
"It's dangerous up there," Tadano said. "The Darks patrol constantly. Anyone caught on the surface—"
"I know, I know." She waved a hand dismissively. "But don't you ever just... want to see it? The world they took from us?"
Tadano didn't answer immediately. The truth was, he thought about it constantly. Every single day of his sixteen years had been spent underground, breathing recycled air, living in the dim glow of light-stones and runic lamps. He'd trained his whole life, pushed himself to be the best swordsman in the village, honed his skills until he could best even magic users in combat.
But for what? To live and die in these tunnels? To hide forever while the Darks ruled the world above?
"Yeah," he admitted quietly. "I wonder."
Vivi looked at him, something fierce and determined burning in her amber eyes. "Then maybe," she said, "we should stop wondering."
Before Tadano could ask what she meant, they reached their quarters. But as he pushed open the door, he couldn't shake the feeling that something was about to change.
Something big.
And knowing his sister, it probably involved fire.