Chapter 8: Alliance in Mist

Suddenly, this newly appearing Demon Slayer filled Seina with joy and determination. Her tired and bruised body was welling up with energy since she knew she wasn't going to be alone in fighting Kuro. The Slayer was a young man with piercing green eyes and short messy black hair; it showed confidence without words. His Nichirin blade gleamed pale gold under the misty sun.

"You've been holding up well," the Slayer said, his tone even. "But this demon is no ordinary foe."

Seina nodded, her breathing steadying. "It's stronger than anything I've faced. Its techniques are refined—almost human."

"That's because it's not just any demon. I've been tracking it for weeks," the Slayer replied, his gaze locked on Kuro, who observed them with a mixture of amusement and annoyance. "I'm Haruto, by the way."

"Seina," she responded quickly, her eyes never leaving Kuro. "Any plans?"

Haruto smirked. "We take it down together. Stay sharp."

Kuro's lips curled into a smile, its razor-sharp teeth glinting in the pale light. "So, you've brought a friend. How quaint. This just makes it more interesting."

With that, Kuro shot forward-much faster than either Slayer had anticipated. Haruto blocked the first attack; the sound of steel to claw rung loudly within the hall. Seina tried circling behind the demon, cloaking with her Mist Breathing as she struck with precision toward Kuro's torso.

Kuro dodged fluidly with calculated motions. "You think numbers are going to make this fight easier for you? I show how wrong that is."

In one smooth motion, his arm cut through the air and released a wave of dark energy that sent both Slayers sliding backward. In an instant, however, Haruto's blade flashed in an assault.

"Sun Breathing: Blazing Cascade!

A storm of burning slashes streamed from his sword and illuminated the battlefield, forcing Kuro to back off. Seina immediately exploited this opportunity to execute her technique.

"Mist Breathing: Sixth Form—Shifting Haze!"

But in an instant, she had become a blurred figure, darting around at impossible speed around Kuro-the demon was growling furiously because, with Haruto's relentless attack, he couldn't track her.

Now, their combined efforts were driving Kuro off, but far from defeated, the dark aura of the demon grew heavier, his movements increasingly hazardous and wild.

"You're better than I expected," Kuro finally admitted, his tone full of grudging respect. "But you're still outmatched.

Kuro's body began to twist and his muscles bulged as his form grew ever more monster-like. His eyes shone bright with an unholy light, his claws extending into more jagged, blade-like talons.

Seina and Haruto looked at each other once, certainly-the battle was on now.

"Don't let your guard down!" Haruto yelled as the flame blade ignited even brighter. "Keep your feet about you, and just keep moving!

Seina nodded, her Mist Breathing technique keeping her agile as she danced around Kuro. The demon was faster now, each swipe of his great claws tearing gashes into the ground. On the frontline was Haruto, his flame-wreathed blade ringing loud against Kuro's talons.

The battle still raged on as Seina watched Kuro. He favored his left side; his right arm was a bit slow to move. Weakness? Trap?

She was going to bet on it.

"Haruto!" she called. "Its right side-it's slow! We can take advantage of it!"

Haruto didn't hold back, shifting into another stance that wholly directed his attack to Kuro's right side. The demon snarled, his eyes widening in surprise as he realized he had been left open. Seina joined the attack, her sword dancing through the mist and striking with calculated blows.

For a moment, it seemed that they truly did have the better of them; Kuro's defenses were faltering and its movements far more desperate. But victory was just at hand when the glowing sigil seared into the ground flashed once more.

"No!" Seina shouted, late in realizing what was happening.

The energy from the sigil surged, covering Kuro with a dark, pulsating aura. The demon roared in triumph as his power increased exponentially. The wounds they had inflicted began to heal, the damage undone by the unholy magic of the sigil.

"This is bad," Haruto muttered, clenching his grip on his blade. "We need to destroy that sigil, now."

Seina and Haruto fell back for a moment, trying to work out their next step.

"I'll distract Kuro," he said. "You get on with the sigil. If we can break its connection, we might have a chance."

Seina considered it; her eyes moved from Haruto to the demon and back. "Are you sure you can handle it alone?"

Haruto smiled reassuringly. "Trust me. Just do your part."

She nodded reluctantly, her eyes on the sigil. With a cautious approach, she neared the markings, her blade at ready. The welling smothering darkness from the markings had almost taken her breath away, yet onward she pressed, intent upon her mission.

Mist Breathing: Fifth Form—Sea of Clouds and Haze," she whispered, her blade slicing through the air in a series of graceful arcs. It was enough to disturb the sigil's energy and made it flicker.

Haruto fought Kuro head-on, the flame imbued in his blade clashing against the demon's strength. With every strike, he was brought closer to his limit, yet refused to give in.

"Hurry up, Seina," he muttered under his breath. "Come on.

With every strike, Seina's blows against the sigil grew stronger: chips and crumbs of the markings fell off, oppressive energy repelled with each blow. That was going to be some very slow process, and Kuro wasn't about to let it go without notice.

In one instant, the demon tore itself from Haruto, claws outstretched towards Seina. Barely in time to react, her blade rose-about a second late to block it. She felt the power and stumbled a step backward, but kept her footing.

"Not so fast!" Haruto yelled, intercepting Kuro with a vicious slash. Howling with pain, it was off him once more.

"Seina, finish it!" he called, his voice strained.

Summoning the last bit of her energy, Seina raised her sword for the finishing blow.

"Mist Breathing: Eighth Form-Obscuring Typhoon!"

A cut sharper and quicker than before tore through the seal in a pace and a fashion that it had never been used-storm of mist and steel tearing through. The markings crumbled, dark energy dissipating into the air.

Kuro let out a pained roar as the power of the sigil abandoned it. Slowed down, the demon's movements turned slow and incoordinated. Haruto took this chance and executed his strongest technique.

"Sun Breathing: Solar Inferno!"

A flash of light blinded everyone, and after it was gone, there was only ash from Kuro's body being incinerated by the highly intensive power.

In the ensuing silence, bruised but triumphant, were Seina and Haruto standing. For the time being, the village was safe.

"Good work," Haruto said, flashing her a worn smile. "You have potential."

Seina could do no more than a slight smile in response. "Thanks, I couldn't have made it without you.

As they went down the stairs, further toward the cellar, this feeling that this was just the beginning only increased in Seina. The words of Kuro, that the sigil was a "doorway," still kept ringing in her head-a sort of foreboding of what was going to be.