The roar of the massive airship's turbine engines echoed throughout the chamber, like the heartbeat of an unending machine.
On the training deck inside the Aethertech Academy's carrier — the academy's main combat arena, nearly half the size of a hangar — two figures stood facing each other on a floor of magnetized steel.
Dim white lights glowed from the high, dome-shaped ceiling, illuminating a faint mist from the energy-field generators. The surrounding walls were made of reinforced transparent glass, with power cables running across their surface like metallic veins.
On the right side of the arena, Harusa stood steady, her breathing calm but tense. The Karl-9A, a heavy metallic-purple rifle, was gripped tightly in her hands. Her gaze was sharp and focused — though a hint of nervousness lingered beneath the surface.
On the left stood Aru, posture straight and resolute. Her massive shield, bearing the golden bird insignia of Primanoel, gleamed under the white light. Hot steam hissed faintly from the generator mounted on her back, making her look like a warrior freshly forged in an engine room.
From the upper observation platform, Kaito stood silently with his arms crossed. Beside him, Rio crouched by a digital console directly linked to the airship's surveillance system, his eyes glued to streams of data and energy-field graphs.
Aru took a single step forward, her voice echoing through the hum of the engines.
"Don't hold back, Harusa. I won't hold my shield back either."
Her tone was deep and commanding — the kind of voice that could cut through the noise of war.
Harusa arched a brow and powered up her Karl-9A. The weapon's inner mechanisms spun with a sharp metallic whirr.
"You asked for this duel. Don't cry later when your fancy shield turns into scrap metal, Primanoel."
Rio snorted softly, his fingers flying across the console.
"Alright then, let's see which one's faster — the bullet or the ego."
Kaito said nothing, his eyes tracking every small movement in the arena below. The exhaust wind from the turbines above occasionally swept down, brushing the edges of his long blue coat.
---
The duel began.
Harusa crouched slightly and fired.
Metal bullets slammed into Aru's shield in rapid succession — TAK! TAK! TAK! — bouncing off and scattering across the steel floor, sparks bursting into the air.
Aru didn't budge an inch. She rotated her shield with perfect control, her body moving in sync with the ship's artificial gravity.
No matter where Harusa shifted, the shield was always there — precisely in line with the next shot.
"Those reflexes aren't human," muttered Rio, narrowing his eyes. "That shield's running on a magnetic-core servo. It calculates trajectory angles in real time."
Harusa clicked her tongue.
"Damn it, it's like shooting at a wall that can think."
She sprinted to the right, her combat boots clanging on the metal floor. The Karl-9A roared again, spitting heated rounds — but Aru advanced steadily, rotating her shield with disciplined precision.
Then — BAM!
Aru slammed her foot down and lunged forward like a living bullet of steel.
Her shield swept horizontally, slicing through the air with a force strong enough to blow Harusa backward.
"Harusa, keep your distance!" Rio shouted, his monitor flashing spikes in air pressure.
"I know!" Harusa snapped, frustrated but unyielding.
She fired at Aru's feet — the bullets punched through the steel plating, scattering sparks — but Aru had already activated her shield's generator.
A sharp electrical hiss followed. BZZZT!
A shockwave rippled through the air, rebounding off the glass walls.
Harusa let out a small cry as the current raced across the metal floor, jolting her legs. She jumped back, limping slightly.
Rio's expression tightened as he analyzed the readout.
"That shield's not just for defense… it's a close-range weapon. Output's around twenty thousand volts."
Kaito remained silent, but his crossed hands slowly clenched.
"She's losing focus," he said quietly. "She's fighting too hard not to disappoint me."
Rio glanced up at him.
"Then maybe she needs a better reason to win," he murmured.
Harusa switched tactics. She pressed a small button on her Karl-9A and dropped it to the floor.
The weapon continued firing automatically, its system engaging from a static position — bullets whirring through the air in rapid bursts, hammering Aru's shield relentlessly.
Meanwhile, Harusa dashed in a wide arc, drawing a smaller pistol from her belt.
Aru deflected the stream of bullets, unaware that Harusa had repositioned to her right.
BANG!
The small pistol's round ricocheted off a steel wall and struck the edge of Aru's shield.
Metal sparks scattered.
Harusa smirked faintly.
"First bounce successful."
She fired again. This time the bullet bounced twice — off the wall, then the ceiling, striking the back of Aru's shield.
One shot grazed Aru's shoulder.
Rio grinned. "She's calculating ricochet angles! She's finally back in rhythm!"
But Harusa's breathing was growing heavy. Sweat trickled down her temple, and behind her, the Karl-9A sputtered to a stop from overheating.
Aru stood unmoved. A crack split the right edge of her shield, but her eyes were still sharp.
"That's enough, Harusa. I don't want to hurt you here."
"Heh… you sanctimonious commander," Harusa muttered, firing once more — but the shot went wide.
Aru closed the gap in an instant.
With a single powerful motion, she slammed her shield into Harusa's chest — BOOM!
The impact sent her flying across the metal floor, rolling until she hit a support beam.
Rio instinctively reached for the emergency override, but Kaito stopped him.
"Don't. Let her stand on her own."
Harusa looked up toward Kaito on the upper platform. His cold, unreadable stare struck something deep in her chest.
❝I can't let him down…❞ she thought.
Breathing hard, she pushed herself up, gripping her pistol with trembling hands.
But Aru was already there.
The shield swung once more — this time, with full force.
The metallic impact echoed through the hangar.
Harusa crashed to the floor, her weapon clattering away. The arena's system instantly marked the defeat.
Overhead lights dimmed, and the alarm ceased.
Kaito stepped into the arena, his boots echoing softly on the steel floor.
He stopped before Harusa, who sat gasping for breath, and said flatly,
"Battle isn't about good intentions. It's about how you stand after you've fallen."
Harusa lowered her gaze. Her shoulders trembled — partly from exhaustion, partly from frustration.
Aru watched them quietly, then placed a small envelope on the floor.
"If you wish to know what data lies within our chip," she said calmly, "come to Primanoel with this letter."
Her eyes met Kaito's. "But bring a reason worthy enough to open it."
Without another word, Aru turned and walked toward the exit.
The metallic door slid shut behind her with a soft Ssshhhk!
Rio exhaled, closing the console.
"Well… at least the floor didn't explode. But you two almost made Aethertech's training deck tomorrow's headline."
Kaito didn't respond. His gaze rested on the letter — that small object that might hold the key to the next mystery.
In his gray eyes, the faint reflection of the Primanoel emblem shimmered.
❝Primanoel again…❞ he thought coldly.
❝And this duel was just a cover for something deeper.❞
---
[Ten Minutes Later]
The airship's engines thrummed softly in the background, their vibrations resonating through the metal walls.
Dim bluish-white lights reflected off the control glass, revealing a breathtaking panorama of pale sky stretching endlessly beyond.
Kaito stood before the wide observation window, arms crossed, his long blue coat swaying gently as the ventilation system breathed overhead. His eyes were distant, searching beyond the thick glass — as if looking for something far beyond the horizon.
A few meters behind him, Harusa sat on the cold floor, her back against the wall. Her breathing was still uneven, and her right hand trembled slightly as it gripped the Karl-9A. Beside her, Rio crouched with a small holographic tablet, replaying the duel's footage. The blue glow from the screen flickered across his calm yet focused face.
"You know, Harusa…" Rio said casually, his voice blending with the soft hum beneath the floor. "Aru usually doesn't leave right after a duel. She probably went to the Strider Room to analyze her shield data. So if you wanna catch her — I dunno — maybe for round two, you might still make it."
Harusa didn't reply. She only exhaled softly, her twin ponytails falling over her tired face. Her eyes were heavy — not from injury, but from disappointment in herself.
Footsteps echoed on the metal floor. Kaito approached slowly, standing behind her. His voice was calm yet firm.
"Harusa," he called, "don't waste time regretting what's already over. Everyone has their breaking point."
Harusa looked up weakly, her eyes still red.
"But, Teacher… I was stupid back there. I knew she was stronger, and yet I still—"
"—attacked out of emotion," Kaito interrupted, his gaze fixed on the drifting clouds beyond the glass. "I know that feeling. I once did the same."
Rio paused his typing, glancing toward Kaito. Harusa's eyes lifted, searching his expression.
Kaito inhaled deeply. The steady rhythm of the ship's engines grew louder as he spoke.
"When I was a commander, my unit had one rule: Don't disappoint me. They fought in my name, for our reputation. We won — again and again. But…"
He fell silent for a moment, his reflection faint in the glass.
"Every victory cost lives. Until I realized… I was winning in numbers, but losing in meaning."
Harusa listened quietly, every word sinking in.
"So… what did you do then, Teacher?"
Kaito turned slightly. His tone softened, though his eyes stayed firm.
"I changed my unit's rule. From Don't disappoint your commander to Honor the pride of your enemy. Because if you can respect your opponent, you can respect yourself."
He lowered his gaze. "And that's when I learned — war only means something if there's still humanity in it."
The room fell silent. Only the low rumble of turbines filled the air.
Harusa looked down, then slowly raised her head again. Her face was calmer now, her eyes regaining their focus.
"'Honor the pride of your enemy,' huh… sounds strange, but… I think I get it now."
Rio chuckled lightly, tapping his tablet.
"Heh. Old-school wisdom, but not bad. Maybe I'll name my next algorithm after that — Honor Protocol, Version 1.0."
Kaito shot him a flat look, then turned back to Harusa. He gently patted her shoulder.
"If you truly want to make things right, don't stop just because you lost once."
Harusa nodded, then took a deep breath. Her voice was softer now, but resolute.
"Teacher… I didn't join the Juantice Team just to fight. I… want to capture someone."
She tightened her grip on the Karl-9A. "My sister, Hanako. She's a wanted fugitive across all the academies."
Kaito went silent, his gaze thoughtful.
Rio lowered his tablet slightly, his tone turning serious.
"Hanako…? That name's in Aethertech's old archives. If she's still active, we can trace her through Sigma's leftover Strider data."
Kaito looked at Rio, then back at Harusa.
"In that case," he said quietly, "we have a good reason to stay on this ship a little longer."
The hum of the airship deepened, joined by the soft hiss of hydraulics along the walls.
From the vast window behind them, sunlight filtered gently through the clouds — glinting off the Karl-9A lying beside Harusa.
It shimmered faintly, marking the end of one battle… and the beginning of another mission — one none of them yet understood.