"Fine."
Mio Takamiya slowly raised her pale, delicate hand.
Her lips, previously sealed in silence, parted slightly.
Her silver-blue eyes narrowed to slits—sharp as blades drawn from a frozen wasteland, glinting with a chilling killing intent.
As her hand fell with her words, the environment around them instantly shifted.
Space warped subtly.
Strange colors radiated outward from Mio as the center, spreading in waves.
The world lost its color for a brief instant—then was re-painted in tones of black and white.
"My personal domain has always been active," Mio explained, her tone calm and detached, like a true final boss.
"It exists just beyond the boundary of this world, like a thin veil. Now I've summoned a portion of its core here. Which means… this whole area is now the Neighboring Realm."
What she'd summoned was only a fragment of her true power.
If Mio fully manifested her Angel and the complete domain of Reiryoku, it would cause catastrophic damage to the Earth.
In the original Date A Live novel, Westcott once mentioned before Mio's appearance:
"The spatial field this Spirit is about to bring forth… is large enough to cover the entire Earth."
If Mio had truly intended to rule the world, she could easily have blanketed the planet with her domain and become a literal god of Earth.
"A pretty decent battlefield," Nagami said with a casual smile, slowly rising into the air.
The purple six-pointed star spun gently in his pupils, and similar star arrays appeared throughout the surrounding space—reflections of the same eye.
Since this was agreed to be a one-on-one duel, Mio naturally didn't pull Kotori into the Neighboring Realm as well.
Nagami wasn't particularly guarded against Mio's actions either.
After all, at this point in the story, he was the one playing the villain.
If something were to go wrong in this fight, it would probably be his fault for not playing fair.
Strike them first before they strike you—then you're never caught off guard.
Honestly, being the bad guy was way easier than playing the hero.
Still, for now, things hadn't gotten to the point where dirty tricks were needed.
"…The physical constants… and laws of the world… they've changed."
With his eyes, Nagami could clearly see the rules that now governed the area.
If this had happened in the regular world, such drastic deviations in physical constants would've caused the collapse of reality itself.
But this domain held together—thanks to Mio's will, which enforced the altered laws of nature.
If she ever expanded the Neighboring Realm to encompass the universe… she would essentially become like a Magic God from the Index universe, with the ability to rewrite physical laws at will.
Nagami nodded thoughtfully and took a deep breath.
"Well then… shall we start the game?"
With that simple, matter-of-fact declaration—so very Blank-style, Nagami ascended to an altitude of nearly a thousand meters and extended his hand.
From the void, glowing azure particles began to gather at his call.
They clustered and coalesced into a massive, strangely-shaped projectile—dozens of meters long.
His first move, taking inspiration from the Blank siblings and Komiya Koyuki's "first game" tactic:
'Start with a hydrogen bomb—just to show some goodwill.'
Due to the altered physics, it wasn't impossible to use advanced energy weapons like railguns requiring planet-based firing anchors, but recalculating the formulas would take ages.
In contrast, nuclear weapons like hydrogen bombs were weapons Nagami, who suffered from firepower insufficiency phobia, knew inside and out.
They were simple, efficient, and devastating.
Even better, with the battlefield sealed within the Neighboring Realm, he didn't have to worry about fallout or radiation contamination.
Which meant… he could go all out without consequences.
"…Hmm?"
Mio narrowed her eyes slightly at the bullet-shaped weapon formed entirely of compressed energy.
Her brow furrowed with faint puzzlement.
In the Date A Live universe—where magic users and Spirits dominated—the technological path was… let's say, "a little off."
The strongest weapons of this world belonged to the realm of magical systems.
And Nagami wasn't the type of villain to give long-winded skill explanations.
So it was perfectly reasonable for Mio to be a little confused by what she was looking at.
'BOOM!!!'
An explosion of pure light and heat detonated mid-air.
A blazing fireball engulfed the city, and then a monstrous column of flames erupted upward—devouring oxygen, launching debris and dust skyward.
The base of the inferno sucked in air violently, forming a massive, rising mushroom cloud.
Concentric rings of white fog spread out in every direction with terrifying speed, trailing behind the shockwave.
"…I get the feeling my combat style's kinda weird," Nagami muttered, as he reformed his body using the powers of the Herrscher of Reason, staring up at the boundless firestorm raging in the sky.
Nagami couldn't shake the feeling that if he were playing a game with Ellen, they should be clashing giant swords in an all-out brawl.
"…No, no. That's what those uncultured pseudo- herrschers would do. I'm a man of refinement."
Muttering to himself, Nagami shook his head, dismissing the image of brutish combat from his mind.
His gaze drifted toward Mio Takamiya in the distance—but the six-pointed star in his pupils locked not onto her, but the massive, towering structure rising behind her.
Her angel, Ain Soph Aur, shimmered with glassy, rainbow-like brilliance.
From the cracks in its structure, a spirit core resembling a young girl almost like a tree spirit—could be seen.
This was the birthplace of the "Arbitrary Realm," and the very origin of the ten-element Spirits.
"As expected of the First Spirit's angel. You actually tanked a hydrogen bomb without breaking a sweat."
Though it hadn't been the most powerful nuke, it was still humanity's ultimate weapon.
Nagami's praise was genuine, but Mio remained silent, unmoved by his words.
…Because it hadn't been that easy.
Suddenly, the wind turned razor-sharp, cutting like blades and laced with killing intent.
Eight branch-like projectiles sleek and sharp like swords materialized from the void and launched toward Nagami with lightning speed.
These were Branch Blades, a superior technique from the Reincarnation Eden.
Each blade possessed enough power to kill a Spirit.
The branch-swords tore through Nagami's body only for his figure to vanish seconds later.
A mere afterimage.
His real body darted across the sky like a bolt of lightning.
Agile and swift, Nagami twisted mid-air, narrowly dodging a blade that would have impaled him.
Wreathed in electricity, he formed a gun shape with his thumb and forefinger.
Energy surged to his fingertips and fired like a laser cannon—brilliant, concentrated, and devastating.
When the beam struck the branch sword, it erupted in a blinding explosion of light.
"Oh?"
Mio's brow furrowed slightly, surprised by the attack's force.
Nagami was a bit surprised too.
That shot had been no ordinary blast—it had struck at the atomic level.
The attack targeted the very structure of matter, annihilating negatively charged electrons with positrons and releasing immense energy—light, gamma rays, heat.
It was meant to unravel atomic cohesion itself.
In simpler terms: it was a positron cannon.
This was something C.C. had been trying to teach Mei and the other Herrschers for a while now… but unfortunately, the lessons weren't going so well.
Every time things got tricky, Mei always ended up taking the fall.
"Please, I'm counting on you… other me."
Since Mei and her other personality were technically the same person, if one of them learned it, the other would too—eventually.
Among all the Herrschers, only "Flip-Flop" and "Pufferfish" had that kind of dual-identity relationship.
The rest were more like two sides of a coin.
Another positron cannon fired—obliterating another incoming branch-blade in a dazzling burst.
Then, wrapped in roaring lightning, the Third Herrscher—Nagami—shot through the sky like a meteor, charging straight toward Mio.
As he activated the Herrscher of Thunder's power, storm clouds gathered overhead, bursting with streaks of violet-blue lightning.
That electricity surged into his hand, condensing into a brilliant spear of pure thunder.
Even in close combat… the aesthetics of battle could remain stylish.
Nagami had drawn inspiration for this move from an old manga in his previous life—"Sea Tiger."
Electric pulses crackled like drumbeats as Nagami dragged dozens of magnetic fields with him.
As the magnetic forces spiraled and rotated, they amplified the explosion of violet-blue energy—turning into a radiant, blinding blade.
It wasn't just a thunder spear anymore, it was a Magnetic Godslayer Blade, a weapon wreathed in destruction and death.
"I swear to God—MAGNETIC HEAVENLY BLADE!"
Because, honestly, martial arts moves like this just feel wrong without yelling something ridiculous.
As if plucking a flower, Mio calmly extended her hand toward the spirit tree at her back and snapped off a unique, glowing branch.
With a low, high-pitched screech, icy-blue sword light flashed through the air.
She wielded the branch as a blade, and with a sweeping motion, slashed a wave of energy that split the sky like a curtain.
Her blade collided with Nagami's violet-blue thunder slash—
A deafening boom rang out as the clashing energies exploded, shockwaves and lightning bursting in all directions in a maelstrom of force.