Part one hundred fifty seven — Nero

　Something struck at Kai's head with lethal speed the instant the barrier's function changed――Null-Subconsciousness's own automatic defense barrier flaring up just in time to stop it.

　Enzo closed the distance instantly, meeting the attacker head-on, the two of them clashing like actual storms breaking across the sky.

"Who is that?" Kai said, disbelieving, watching the fight unfold.

　Vance was shaking where she stood, visibly terrified.

　<Appraisal complete. The unknown entity is a primordial demon, designation No.8.>

　Null-Subconsciousness's report came without hesitation.

　Enzo held his own against the second-strongest primordial demon in existence, unleashing an attack called Storm Break――No.8 simply laughed and deflected it aside, the resulting force leveling a nearby mountain range instead.

　He appeared directly in front of Kai a heartbeat later.

"You've grown into such a wonderful child."

　Kai's blade materialized instantly, aimed to cut through him――but No.8 was already at his back before the strike could land.

　Null-Subconsciousness released two percent Null mana, and the two of them faced each other properly for the first time, Enzo stepping back to let Kai handle it himself.

This guy isn't even taking this seriously.

　Kai thought, flashing back briefly to Vance and Enzo's side.

"Wow. This guy is bad news."

　No.8 hung in the air above him, considering, before descending――and stopped short the instant Nyxara appeared, her fury toward him immediate and unmistakable.

"Dear big sister," No.8 said, entirely unbothered, "is this how you greet your twin brother after all these years?"

"Twin brother?" Kai said, disbelieving. "I never knew you had a twin brother, Nyxara."

"It's complicated," she said, flat.

　Demon Lord Ravessia appeared above them next, studying No.8 with something unreadable in her expression.

　Vance, having now witnessed three primordial demons in human form within a single afternoon, simply fainted outright.

　Ivy, Eris, Elaine, and Ace arrived moments later, drawn by the sheer scale of the disturbance.

"Oh, what a lovely welcoming party," No.8 said, delighted. "Come at me――I'll take on all of you."

　He genuinely could have.

　Only Ravessia, Nyxara, and Enzo posed any real threat to him among those gathered.

"Not happening," Kai said. "I'll be the one facing you."

"Are you certain?" Ravessia asked. "His strength is roughly equal to my sister's."

"You're joking," Kai said.

"Not exactly," Ravessia said. "The only reason she's technically ahead of him is her Demon Lord advantage. She's considered equal to Divo and the Primordial Time Dragon――Aeon, though we usually just call him the Unknown."

No.8's that strong.

Well. I don't care. I'm still defending what's mine.

"Good," No.8 said, grinning. "Let's begin."

"I'm ready when you are," Kai said. "Got something new to try, actually."

　Null-Subconsciousness took full control.

　Kai's aura turned crushing to everyone present except Enzo, Ivy, Ravessia, No.8, and Nyxara.

　No.8's grin only widened.

"This will be interesting."

　Null created its own dimension――Vermilion, saturated entirely with Null mana.

　Yet No.8 seemed entirely unaffected. Negation had nothing to negate against something already built from the same principle.

　The fight was merciless, blade meeting bare hands through exchange after exchange, until Null activated its ultimate attack.

Eclipse.

　The sky darkened unnaturally.

　A black sun rose above the battlefield, ringed in gold, and silence fell total across the dimension.

　Umbral Dominion swallowed vision and senses alike.

　Solar Judgment tore through anything solid.

　Gravity of the Eclipse pulled everything inward toward its center.

　Twilight Chains erupted from the ground, binding and draining.

　Lunar Mirage scattered false targets through the dark.

　Corona Burst released a blazing ring of solar fire, incinerating everything in its path.

　Then came the final move――

Eternal Eclipse.

　The black sun swallowed all remaining light.

　Time itself seemed to freeze.

　Then it collapsed into a single point――

　――and exploded outward in a colossal wave of black and gold.

　It landed cleanly on No.8.

　He survived with barely a bruise on his cheek.

"Impressive," he said, smiling. "Fine――you win. I was only testing you."

　Null-Subconsciousness released control, and Kai, back in his own body, stared at him in open disbelief.

"You were testing me? What the――that's not how you test somebody!"

"Chill out, dude," No.8 said.

"Don't tell me to chill out, you almost killed me."

"Fair. I apologize," he said, laughing anyway. "Truth is, your mother asked me to look after you."

　Kai went still.

"Wait――you're the one who fought her?"

"Yes."

"And you lost."

"I didn't, technically," No.8 said. "I went on a rampage. My older sister stopped me. Your mother's the one who sealed me away."

"Then why would she ask the same person she fought to look after me?"

"Before she died, she reached me through thought, asking me to watch over you――because half her core was already inside you, keeping the chaos from overtaking your mind. She's the Chaos Dragon, after all. I agreed. I've been watching you this whole time, from inside the barrier."

"Dragons are supposed to be reborn elsewhere when they die, right?" Kai asked.

"Yes."

"Is it because her core's inside me that she hasn't come back?"

"Yes."

"If I removed it, would she return?"

"Yes," No.8 said. "But that would be a mistake. That core is the only thing keeping your Null mana from destroying this entire world in an instant. That's the real reason I've been keeping watch."

　Kai placed a hand over his own chest.

"As long as she's safe inside me, that's all that matters."

　A pause.

"What about my dad?"

"I don't know," No.8 admitted. "Could be alive. Could not be."

"Anyway," Kai said, "let's get moving. I've got a project waiting."

"Quick question first," No.8 said.

"What?"

"Your Null mana bypasses the laws of evolution entirely, doesn't it?"

"You really have been watching," Kai said. "What do you want?"

"A name," No.8 said. "I'm tired of being called No.8. This body's getting old anyway."

"Null," Kai said, "can I actually name him?"

　<You referred to me as Null,> it observed.

"Just answer the question."

"Are you kidding me? I can barely manage two percent on my own."

　<I recommend the Unique Skill Absolute Null Throttle,> it offered.

"Do it," Kai said.

　Null mana surged to twenty percent.

　Kai's aura expanded dramatically――even No.8 whistled, impressed.

"What did that woman actually give birth to."

"Ready?" Kai asked.

"Don't have to ask twice."

　Kai considered for a moment.

"Nero."

　<"Naming complete. Evolution condition fulfilled. Primordial Demon No.8 has transcended his racial limitations.">

　Complex spellwork surrounded him instantly.

"He can evolve?" Kai asked.

　<"Yes," Null-Subconsciousness said. "Select an evolution path. Option one: Primordial Demon of Oblivion. Option two: Null Demon Lord.">

"Wait, there are options now? Can I pick both?"

　<"Yes.">

"Then I pick both."

　<"Evolutionary fusion complete. New species confirmed. Designation: Abyssal Demon Emperor.">

"...Damn," Kai said. "That's badass."

　Nero opened his eyes, something visibly different settling behind them.

"It's a pleasure to serve under you, Lord Kai."

"Not you too," Kai said, rubbing his forehead.

　The dimension released.

　Nyxara and Ravessia both sensed something had changed immediately.

"What happened to No.8?" Nyxara asked.

"It's Nero now," he said, smug. "Get used to it."

　Eris groaned.

　Elaine sighed.

　Enzo said, "Saw this coming."

　Vance, waking briefly, took one look at the situation and fainted a second time.

"How are you even able to name a primordial demon?" Ravessia asked.

"I'm as confused as you are," Kai admitted.

"Which path did you take, Nero?" Nyxara asked.

"Abyssal Demon Emperor," Nero said, delighted. "Meaning I'm now equal to, or possibly above, you, big sister."

"In your dreams," Nyxara said.

　Ivy, listening closely, filed away the phrase Abyssal Demon Emperor with obvious, private interest of her own.

　Once the chaos settled, Kai used Null Absorption to properly absorb the entire dimensional barrier, along with the remaining half of his mother's core still sealed within it.

　He paused all other product manufacturing indefinitely, redirecting his full focus toward the Genesis Core project――if he could fuse both halves of her core together, she might finally return, and permanently stabilize his own Null mana rather than merely suppressing it from within.

　New land opened up beyond the former barrier, some clear of monsters, some holding creatures nobody had ever catalogued. Elaine began construction on the safe sections immediately.

　She also built an underground facility specifically for Genesis Core production, and Kai spent long stretches there, working, largely uninterrupted.

　Outside, other kingdoms grew bolder――spies probing Horizoncrest's defenses, trade routes quietly obstructed.

　Kai sent Enzo and Eris to Myrath, where ambitious nobles were testing the young prince's authority.

　Elaine, Vance, and Ace held Horizoncrest itself.

　Ivy departed for the Tearmoon Kingdom, representing him at Queen Mirabel's own request, since he couldn't attend personally.

　Nero remained with him in the facility, alongside Seli and the newest cohort of Holy Knights Eris had personally trained.

　Nyxara, meanwhile, claimed Belial's abandoned domain for herself, bringing his scattered followers properly under control.

　Ravessia returned to her own territory, the day's extraordinary events finally, quietly, settling into whatever counted as ordinary now.