The tunnel beneath the Registration Hall was longer than anyone expected.
The moment Satotz led the candidates underground, the temperature dropped — not from chill, but pressure. The kind only intense nen exerted: deep, invisible currents brushing your skin like fingers.
Kaen didn't flinch.
He was studying everything — the vibrations in the floor, the scent of sweat from nervous applicants, the way Gon and Killua walked in perfect harmony despite not speaking.
But it was the gap behind them that set him on edge.
A blank space.
Aura-dead.
Like something was missing from the world.
He's close.
Hisoka.
⸻
"Your first test," Satotz announced calmly, not breaking his stride, "is simple: follow me. Don't fall behind."
Simple?
Maybe on paper.
But the tunnel was already a battlefield — and Kaen could feel it.
Spikes of nen flared every few meters — applicants jostling for space, trying to intimidate, to dominate.
Some sent probes toward Gon.
Others tested Kurapika's calm.
One unfortunate idiot threw a whisper-blade of aura toward Killua — and got a dislocated wrist before the sound even finished.
But no one tested Kaen.
Because his nen didn't look like anything.
It was mirror still.
Untouchable.
Unknowable.
⸻
Thirty minutes in, the tunnel narrowed.
Lights flickered. Dripping from overhead pipes formed rhythmic patterns.
That's when it happened.
A laugh. Soft. Like the wind under a blade.
And then—
"Oooh, shiny soul… What a dangerous little toy you carry."
Kaen turned.
And there he was.
Hisoka.
Face pale and painted, eyes wide with delight, teeth glinting beneath crimson lips.
Aura poured off him like perfume made of razors.
The candidates around them shrank away.
Kaen didn't move.
The tunnel held its breath.
Hisoka stepped closer, inches away.
Their eyes locked.
White gloves.
Do not look into his eyes.
Too late.
⸻
The Zero Mirror activated.
Not on Kaen's command.
On instinct.
And for a moment — a single, perfect second — Hisoka saw himself.
But it wasn't just a reflection.
It was a version of him with no restraint.
Wild. Blood-drenched. Eyes glowing red with pure hunger.
A vision of Hisoka without games. Without rules.
A true predator.
And it made him smile.
"Fascinating…"
He licked his lips.
"You're the one who shattered the eye on Whale Island, aren't you?"
Kaen's blood froze.
He hadn't told anyone.
Hisoka laughed like thunder rumbling in silk.
"You broke the Thread's toy. I heard it scream across the sea."
Kaen stepped back, lowering his hand slightly.
"Stay out of my head."
Hisoka tilted his own.
"Oh no, darling. I'm not in your head. I'm in your future."
Then he walked away — just vanished into the mist.
Leaving behind a room colder than death.
⸻
"…What was that?" Kurapika asked, approaching carefully.
Kaen didn't answer.
Not at first.
But then, voice low:
"The mirror didn't show him his worst."
"It showed him his truest."
Kurapika's eyes narrowed. "You can reflect aura?"
Kaen shook his head.
"Not just aura."
And for the first time, Kurapika looked at him not as a rival — but as a weapon he might need.
⸻
Hours passed.
The tunnel turned into an endurance trial.
Candidates began collapsing. Some gave up. Some passed out.
Gon and Killua never slowed.
Leorio kept yelling, but his feet never quit.
Kaen walked silently, observing the room like it was part of his Mind Palace.
And when Satotz finally said the words—
"Congratulations. You've completed the first trial."
—only half of them were left.
Kaen exhaled.
The hard part?
Still coming.
⸻
That night, they were allowed to rest in an underground chamber.
Kaen sat against the wall, eyes closed — not asleep, but inside the Mind Palace.
There, the mirror from before had shifted.
Now it shimmered like oil on water.
And behind it?
Not Hisoka.
Someone else.
A Council mask stared at him through the glass. Silent.
Unblinking.
Then a voice, old and cracked:
"We see your breach. The feathers burn. The core remembers."
Kaen stepped forward.
"I don't care what you see. You sent assassins to my home."
"No. We sent a warning."
"And now, you are inside the heart of the world."
"Do not let your reflection become the center."
Kaen reached into the glass — and shattered it.
Light exploded.
The mask vanished.
And a second later, a new ability bloomed in his hand.
Mirror Fang.
A counterattack nen technique that launches the opponent's aura back at them with precision timing — but at twice the velocity.
Kaen smiled.
If Hisoka tries again, he's getting a mouthful of himself.
⸻
Outside the Palace, in the real world, the air was still.
Then a whisper:
"It's not the mirrors you should fear…"
Kaen's eyes opened.
And across the room — Hisoka was staring again.
From the shadows.
Grinning.
Like he knew what just happened.
⸻
To be continued in Chapter 13: Trick Tower – Death by Reflection