Date A Live: Starting as Acheron

Do you still remember why Izumo forged these blades?

A mountain composed of various scattered swords fell before the girl's eyes, the fleeting gleam of the blades as they fell illuminating the two red horns on her head. Memories flashed through her eyes, telling the tale of a dance between two planets. A desperate, bloody dance for survival.

Because in times past, the Yaoyorozu-no-Kami descended upon the land, wreaking death and destruction upon our people. Thus, Izumo sacrificed 70,033 lives to forge the Twelve Sentinels, which became the keys to our revolution against the Kami.

In her memories, a brown-haired man wearing a grey coat directed shining blue broadsword of giant proportions to stab through the chest of a titan, felling it in an instant.

First was「真」[Truth], allowing mortals to comprehend law and order and create miracles from their own power.

A small girl with long purple hair held up a blade of pink-white energy wrapped in gold. At her command it emitted a burst of power, sealing an ominous wormhole. 

The second was「天」[Sky], which could turn the heavens into our defenses, creating obstacles for the Magatsu-no-Morokami.

This time, it was the girl herself wielding a spiny sword crackling with purple lightning, impaling a giant serpent and quelling the stormy seas. 

Third came「鳴」[Howl], summoning lightning to tear the sky and mete divine justice.

The girl's eyes clouded over as nine more swords of various sizes flashed through her head.

Then there was「嵐」[Mist].「霜」[Frost].「命」[Fate].「烈」[Flare].「覚」[Thought].「礎」[Root].「千」[Form].「束」[Bind]. And「喰」[Maw]. Together, the Twelve Sentinels seized victory after victory, winning back the land and hope for salvation. Until...

All of them were shattered.

The scene changed to a crumbling city beneath a black sun, the girl falling into its deepest depths. 

Every victory came at the cost of an entire world, and in the end, that entirety was lost. And so Izumo destroyed the Twelve Sentinels to forge two Bearers. 

The girl in the memory, rising from the depths, brandished a new pristine blade of white. In the distance, a monstrously large sword covered in the remains of thousands of smaller blades loomed.

「始」[Origin] and「終」[End].

Izumo then forged 70,047 blades, and in the end, only one could save Izumo. But the road to salvation never existed. You and I both know this. But in their futile resistance, [Humanity] eventually became [Oni]. We pawned everything for the destruction of all.

The girl in the memory, now bearing inhuman horns leaped with inhuman strength, rending both her own blade and the behemoth blade in two. 

So...

Do you still remember why Izumo forged these blades?

The girl looked up, finally shaking off the past memories. Her eyes filled with crimson-stained liquid, slowly dripping onto the hilt of her shattered blade.

Because of a lie. For an ending that never existed. We had long since strode into THEIR shadow, each step one that could never be taken back. Until the last blade is forged into...

「無」[Naught]. 

Her blade, reforged blood-red, swung one last time, slashing the black sun. It drank in its power, reforging itself with [Nihility], then swallowed the girl, the two planets, and everything. 

I knew this world was fleeting. And yet... and yet...