Date A Live: Starting as Acheron

Shidou gasped in pain as Kyo slammed him against the door of the rooftop entrance. "What are you-"

"That's my line, you ungrateful ingrate. What part of the previous thirty minutes didn't make it clear to you that you're nothing but a liability here?!" The infuriated Spirit spat, shaking Shidou's entire body by the shoulder. 

"Ugh… even so, I want to-"

"Help?" Shidou nodded resolutely. "Fine, come to my house next week. Expect nothing but pain to await you-"

BOOM-

The entire building shook as Kotori slammed her halberd into the ground. Kurumi, floating a few feet above her, launched another barrage of bullets. The Flame Spirit easily deflected with the handle of her weapon before launching herself into the air, obviously intent on chasing Kurumi down.

"Um… if you won't let me fight, could you at least go help Kotori?" Shidou asked weakly.

Kyo shot him another glare. "What one should not fear is a god-like rival, but a pig-like teammate."

"Er…"

"You're the pig-like teammate," he clarified slowly, as if Shidou were dull. "And now, Kotori is too. I haven't the smallest doubt that as soon as I try to interfere, she's gonna try and give me a new haircut."

Shidou grit his teeth. "So you're just gonna let them kill each other?!"

"Not a terrible plan," Kyo smirked before disappearing from his vision.

"...you're joking, right?!"

—————I am the dividing line that shifts time and perspective—————

"Ngh…" Kurumi tenderly massaged her newly-reattached arm. Tch. I have to end this battle soon; the amount of time I've stored up is getting dangerously low.

Kotori's face morphed into a scowl. "Is that it? Is that everything you have? You began a fight with ME, and THIS is all that you can muster?! Pathetic."

"My, it seems our little Flame Girl has a few anger issues," Kurumi mocked. Irritate her more; then she'll make more mistakes. Mistakes for me to exploit.

Kotori's eyes narrowed as she raised her halberd to the sky and slammed the end of the handle into the ground. "[Camael: Megiddo]!"

Before Kurumi's grim gaze, the handle of [Camael] wrapped around Kotori's arm, and the bladed portion withdrew into a giant gun barrel, which immediately began to smolder. Streams of fire began to flow into its mouth, forming a glowing ball of energy.

Tch. I don't want to waste any more time here, so I'd rather not use [Aleph]. That means… "My clones! Come to me!" Kurumi raised her hand, summoning a small crowd of clones from the shadows. These ones are about to expire anyway, so they might as well die here for me!

Kotori smiled wildly, the light of her flames reflecting off her eyes as an ominous glow. "Burn her to ashes! [CAMAEL]!" 

The barrel of [Camael], now overflowing with some sort of molten energy, fired. 

The first row of clones was immediately torn apart by the blast, their remnants burning away before they could even hit the ground.

The second row fared no better.

The third? Exactly the same as the first two.

Now, as the stream of flame approached her, Kurumi's eyes finally showed a new emotion. Terror.

I underestimated her power.

Her mind whirled into a frenzy. What if I shot [Aleph] now? No, I wouldn't make it. Can I dodge? No, absolutely not. I should've dominated this battle. As one who presides over the power of time, a mere Spirit of Fire should've been an easy kill. What went wrong?

A certain katana-wielding man appeared in her mind, his eyes sparking with red lightning. Him. His interference ruined everything. Even without that dark power that he wields, his unnatural speed brought ruin to everything.

Yet, as though in protest with her thoughts, another figure appeared. A red-haired girl with oni horns, her blazing halberd pointed at her. No, even if Kyo fought me for most of the battle, she was the one who fought me to the end. I should've killed her easily. And yet, here we are. Why?

Was it… my own hubris?

That was her final thought as the flames finally came near enough to lick at her cheeks. Kurumi closed her eyes and accepted her fate. I'm sorry… Sawa… 

…

…

…

Dying by fire hurt a lot less than I thought it would. When my clones described it to me, they exaggerated it so much. Honestly-

"You can open your eyes now," a bemused voice called.

"Eh?" Kurumi opened her eyes to see a familiar katana sheath, bathed in an otherworldly darkness, splitting the beam of fire mere inches from her face. A certain katana-wielding man held onto the handle of the blade within, firmly fixing it in front of them as the stream of energy finally began to falter.

"I told you; I wouldn't let you die."

Kurumi looked away. "Technically, you said that YOU wouldn't kill me. Saving me from Kotori was never part of your promise." I guess it isn't over for me just yet… so wait for me a little longer, Sawa.

"Oh, spare me," Kyo moaned. Despite herself, Kurumi smiled before sinking into her shadow. I suppose I'll concede this victory to him, then. But just for today.

——————I am the dividing line that shifts perspectives——————

What happened to missing your first shot, huh, Kotori? As he stared down a frowning Kotori, Kyo was in a state of inner turmoil. If I wasn't monitoring this fight from under the cover of [White], Kurumi would've actually died already!

"What is the meaning of this, Kyo? Have you decided that you want to war with me too?" Kotori's displeasure gradually changed into a grin brimming with primal joy. "In that case, I'm more than happy to oblige! Come at me! The loser dies, and the winner takes all! That is the spirit of war!"

"Look, Shidou's naked and dancing around with a sign that says 'I love Itsuka Kotori,'" Kyo said with a deadpan tone, pointing behind her.

"HE'S WHAT?" As Kotori turned her head with a face more red than her own hair, Kyo moved in and immediately whacked her in the head with the blunt edge of [Naught], sending her sprawling to the ground. "AUGH! You…"

"Yeah, yeah. Go to sleep. Sweet dreams, and hopefully they're not of your brother naked." Kyo stared down as Kotori's eyes rolled up into her skull, signaling a successful knock-out. "Now then… SHIDOU!"

"Yes?!" The boy in question peeped out from behind the rooftop door, a slightly uncomfortable expression on his face. "Are Kotori and Kurumi ok?!"

"I can really see where your priorities are," Kyo snarked. "Anyways, the answer's actually no. Get over here and save your sister."

Upon hearing his words, Shidou began rushing over to her side, panic written all on his face. "What's wrong with her-"

Kyo casually tossed [Naught] at him, causing him to face-plant a few inches away from Kotori. "Ah, shoot I missed. Well, whatever. Here's the deal: kiss her."

"HUH?!" Shidou jumped up, his face completely red.

"You heard me." Kyo casually dematerialized [Naught], then rematerialized it in miniature necklace form. "Seal her. Do it now, and you'll save you, your sister, and, most importantly, me, a whole lot of pain in the future."

Shidou looked away bashfully. "But… in order to seal her, I first have to make her-"

"Yes, I'm well aware of how your powers work. And my advice is still exactly the same. Please don't make me spell this out for you; it's already weird enough." Kyo turned away, walking slowly towards the edge of the rooftop. "Now then, I have my own life to attend to. Bye."

And with that, he vanished.