Heaven's Arena.
Kevin hadn't set foot in the colossal building for nearly two weeks, consumed by the dual labors of potion refinement and the meticulous construction of his Nen ability. The moment he stepped through the grand entrance, even before reaching the bank of elevators, he spotted a mop of distinctive white hair waving frantically in his direction.
Killua.
Kevin approached, and the boy, clutching a bag of snacks, scampered over.
"Where have you been? I thought you were dead!" were Killua's first, startling words. After noticing Kevin's prolonged absence from the usual fight circuit, he'd done some light snooping. Kevin hadn't missed a week of combat since arriving.
"Thanks for the concern," Kevin replied with an easy smile. "I was in seclusion, training. Made some decent progress." Out of habit, he gave a subtle, conscious push to his aura, causing it to flare briefly around him—a demonstration meant more for himself, as he knew aura was invisible to the untrained.
In that instant, Killua's entire demeanor transformed. His body went rigid, then he exploded backward in a blur of motion, putting a good ten meters between them in a heartbeat. He landed in a low crouch, his eyes wide and laser-focused on Kevin, his expression one of serious, uncomprehending alarm.
Kevin was taken aback. He immediately let his aura settle back to its normal, placid state.
Killua slowly straightened up, but the surprise and deep wariness didn't leave his face.
"Your intuition is incredibly sharp," Kevin said, genuine admiration in his voice. He'd met many non-Nen users, but none who could sense a shift in aura so acutely and react with such instinctive, defensive precision. Is this just raw talent? he thought, a flicker of that old, familiar annoyance at prodigies surfacing. Annoying little genius.
Killua, having regained his composure, looked at Kevin with a seriousness that belied his age. "What was that just now? That… feeling." He searched for the right word. "I've felt something like it before… from my older brother."
"Ah, that explains it," Kevin nodded, understanding dawning. His online research into the infamous Zoldyck Family had been an exercise in surrealism—a legally recognized assassin clan operating a major tourist destination. The world truly was bizarre. But it also spoke to their formidable power. Clearly, Nen was part of their legacy, which accounted for Killua's preternatural sensitivity.
As for why the boy hadn't been formally taught… perhaps he was too young? Kevin could only speculate. From his understanding, Nen was deeply tied to one's developing personality, worldview, and experiences. Introducing it before those were fully formed could be risky, even detrimental.
"This is a… special kind of energy," Kevin finally said, falling back on the vague, adult answer. "You'll understand it naturally when you're older."
As expected, Killua's face scrunched into a frown of profound dissatisfaction.
"Hahaha!" Kevin laughed, reaching out to ruffle the boy's snowy hair. "Don't look so glum, kid. Growing up is a necessary process."
Killua batted his hand away irritably and took an angry bite of his snack.
"By the way, what floor are you on now?" Kevin asked.
Killua snorted. "170th. I thought you were dead, so I fought a few more matches."
Kevin nodded. "Good. That improves our odds of being matched. Want to go register together? I bet you'd rather fight me now, right?"
"Ha! That's exactly what I want. Let's go, let's go!" Killua's irritation vanished, replaced by pure, competitive fire. He tossed his snack aside, grabbed Kevin's sleeve, and began dragging him toward the registration desk.
Before, the prospect of a friendly spar had been just that—friendly. Now, it was charged with curiosity and ambition. That strange power… maybe he could learn something from it through combat? Killua was supremely confident in his ability to learn.
In a shadowed corner of the bustling arena hall, a tall man with stark black hair stood motionless, his expression a mask of profound gloom. His eyes, hollow and intense, tracked Killua as the boy dragged Kevin toward the registration desk, his gaze lingering on the point where their hands connected.
"No… I cannot act. Father's orders are to observe only."
He muttered the words under his breath, a mantra to suppress the cold, coiling kill intent that threatened to leak from his pores. The few passersby who glanced his way instinctively gave him a wide berth.
"If… if he attempts to teach Killua Nen… then, perhaps…"
He continued his low monologue, rationalizing a dark possibility. At this stage, it was not time for Killua to learn Nen. To eliminate that risk, to prevent contamination… taking action would be the correct course, wouldn't it?
Abruptly, his turbulent emotions stilled, smoothed over by a deeper conditioning. He withdrew a phone from his pocket, the movement mechanical.
"Hello."
"...Yes. I understand."
The call was brief. Hanging up, his expression shifted to one of quiet, resigned regret, the gloom around him deepening into something even more impenetrable.
Registration completed, Kevin bid farewell to Killua. Their match was scheduled for the following day. As two of the arena's more notable draws, a little promotional buildup was to be expected.
Ring, ring.
Kevin's phone, a simple device he rarely used beyond calls and texts, vibrated in his pocket. The caller ID read: Mito.
"Hello?"
"Oh, I see."
"No problem. I'll be right there."
He headed straight for the familiar barbecue joint. A waiter, recognizing him, silently led him to a private room.
Inside, Mito sat staring with grave intensity at a veritable mountain of meat skewers piled on the table before him, lost in thought.
"What's on your mind?"
Kevin's voice made Mito jump. "You've lost all your situational awareness?" Kevin asked, puzzled.
Mito let out a long sigh. "During these two weeks you were in seclusion… I reached the 200th floor." He paused, his voice dropping. "Walking down the hallway there… I felt it. An overwhelming malevolence. It was… bone-chilling."
Kevin understood instantly and guessed the reason for the summons.
Sure enough, Mito looked up, his eyes searching Kevin's face. "What was that? That suffocating hostility? You must know, right? You're… on a different level."
He considered himself strong, but facing Kevin had shown him a wall he couldn't even scratch. Kevin was the most powerful person he knew, so when confronted with that inexplicable aura of dread on the 200th floor, Kevin was his first and only recourse.
"It's embarrassing to admit," Mito continued, leaning back in his chair to stare at the ceiling. "In that moment, all I wanted was to run. For a martial artist… that's the ultimate shame."
He turned his bright, earnest gaze back to Kevin.
"Please. Tell me. What exactly was that?"