The Zoldyck estate on Kukuroo Mountain never knew silence.
Silence, after all, was not the absence of sound—it was the presence of fear. The grinding of stone doors, the shuffle of butlers trained to kill, the whispers of intruders who would never return home. All of it was part of the mountain's living heartbeat.
And at the center of it, beyond the spike gates, beyond the Watchdog of the Hellbell, a boy was training.
Kaien Zoldyck was eight years old.
Sweat ran down his long hair, the strands sticking to his sharp face as he pulled his body up from the edge of a cliff, fingers digging into rock too sheer for normal climbers. His small hands were torn raw, the skin splitting at the knuckles, but he did not cry. He bit down on the pain and dragged himself upward, the muscles in his back flexing with unnatural control.
"Seventeen… eighteen…" He counted in his head, his pale eyes locked upward. The white, clouded irises caught the sunlight strangely—almost glowing. They made him look blind, but the hawk-like focus in his gaze betrayed sharper vision than most humans could dream of.
Above him, Illumi Zoldyck, only a year older, leaned casually against a tree, his hair pinned neatly back. His black eyes watched Kaien climb without expression.
"Your grip is slipping," Illumi said flatly.
Kaien clenched his jaw. "I know."
The rock tore another strip of flesh from his palm, blood trickling down his wrist, but he reached the top with a final heave and rolled onto the grass. His breathing came heavy, shoulders rising and falling, but his face stayed unreadable.
From the veranda overlooking the cliff, Silva Zoldyck watched with arms crossed. The patriarch's towering frame cast a long shadow over the training yard. Beside him, Zeno stroked his beard with quiet amusement.
"The boy has resolve," Zeno remarked. "Doesn't make a sound, even when his body's failing."
"He should," Silva replied, voice low. "He's a Zoldyck. Resolve is the least he can offer."
Kaien lay on the ground, staring up at the sky, listening to his heartbeat slow. The ache in his hands burned, but there was a spark deep in his chest. A kind of pride.
I didn't fall. I won't fall. Not here. Not ever.
Illumi crouched beside him, expressionless. "You're bleeding."
Kaien turned his pale eyes toward him. "And you're stating the obvious."
For the first time, Illumi blinked. Then, faintly, a smile tugged at his lips—barely visible, but there.
The days blended into each other.
Kaien's training was relentless. Climbing sheer cliffs until his fingers broke. Carrying boulders across the courtyard while butlers lashed at his back with weighted whips. Holding his breath under icy water until darkness crept into his vision.
Some nights, he collapsed into bed, his hair soaked with sweat, his muscles screaming. But in the silence of his room, staring at the ceiling, he would whisper to himself:
"I have to be stronger. Stronger than the pain. Stronger than the fear."
He thought of his parents sometimes—faces already fading into fragments. He'd been too young when they died. All he remembered was fire, the smell of iron in the air, and then being brought here, into the Zoldyck walls.
"Family," Silva had said simply, staring down at him. "You're one of us now. You will be raised as one of us. If you survive."
So Kaien survived.
One morning, when he was nine, he was dragged from bed by Gotoh, the family butler. The man's iron grip pulled Kaien upright before he'd even fully woken.
"Today you'll learn the basics of aura," Gotoh said, his tone calm but merciless. "Most children your age would be broken by now. Let's see if you're any different."
Kaien's pale eyes narrowed. Aura. Nen. The whispers he had overheard in the halls. The invisible energy that made the Zoldycks gods among men.
They stood in the courtyard. The cold morning air bit into Kaien's skin as Gotoh placed him across from Illumi.
"Focus your will," Gotoh instructed. "Push it outward. Feel it leak from your body."
Kaien closed his eyes. He felt nothing at first. Just his heartbeat, the ache in his muscles. But then… a warmth, deep inside his chest, like a spark waiting to ignite.
He gritted his teeth, forced it outward. His body trembled, sweat dripping down his temple.
Then suddenly—
A wave of pressure burst from him. Raw, unrefined aura. It lashed outward like a gust of wind. Leaves scattered. A nearby bird squawked in panic and fled.
Illumi's hair rustled slightly in the invisible wave. His black eyes widened for the briefest second.
Gotoh's lips curved faintly. "Interesting."
Zeno, watching from the balcony, chuckled under his breath. "Not bad for his first time."
Silva said nothing, but his sharp gaze lingered on Kaien longer than usual.
Kaien opened his eyes, gasping, and saw Illumi staring at him.
"You're ahead of schedule," Illumi murmured.
Kaien tilted his head. "Does that bother you?"
Illumi's lips curved again—something between a smirk and a sneer. "Not yet."
That night, Kaien sat cross-legged on his floor, sweat dripping from his chin, trying to feel that warmth again. He could sense it faintly now, flowing through his veins, wrapping around his body.
This power… it's mine. I'll master it. I have to.
For the first time, he smiled to himself. Not wide. Just a faint curve of the lips. But it was there.
Years blurred.
Ten. Eleven. Twelve. His frame grew taller, shoulders broader, muscles carved by endless discipline. His hair reached the middle of his back now, tied loosely when he trained. His pale eyes unsettled everyone who met them—even some butlers avoided direct eye contact.
He sparred with Illumi daily. Sometimes he lost, sometimes he won, but always he grew sharper. His twin sickle-blades became extensions of his hands, their edges flashing like silver arcs in the training yard.
One afternoon, Kaien disarmed Illumi with a flick of his chain-sickle, dragging the blade to Illumi's throat.
Illumi didn't flinch. Instead, he smiled faintly. "You'll make enemies fear you."
"Enemies should," Kaien replied.
From the balcony, Silva watched, silent as ever. Zeno, however, let out a low laugh.
"Mark my words, Silva," Zeno said. "This one won't just survive. He'll change the way people talk about us."
Silva's eyes narrowed. His gaze followed Kaien as the boy lowered his weapon, pale eyes calm and cold.
"…We'll see."
But it wasn't until Kaien's first mission—his first real assassination—that thefamily truly began to whisper about him.
He was twelve. His target was a corrupt noble who had fled deep into a fortified mansion surrounded by guards. Silva gave the order with his usual detachment.
"Go with Illumi. Finish it cleanly."
Kaien's pale eyes gleamed. His heart thundered, but he kept his face calm.
As the gates opened, as the night wind swept across his long hair, Kaien thought to himself:
This is it. No more training. No more preparation. Tonight… I kill.