Rumors of demons lurking in Natagumo Mountain had been circulating for some time. The Demon Slayer Corps had dispatched multiple squads to investigate, only to discover an abnormally large number of demons within the mountain.
Under normal circumstances, demons never group together. They hunt alone, fiercely territorial by nature.
Most demons possess similar levels of power, and all share the same regenerative immortality. Even if conflicts occur among them, the fights rarely resolve decisively. For a demon to subjugate others, it must possess overwhelming strength—only then can it forcibly gather lesser demons under its command.
The demon cluster within Natagumo Mountain could only mean one thing: a dominant demon powerful enough to force the others into submission.
For this reason, Ubuyashiki Kagaya made a rare decision—dispatching ten Demon Slayer Corps members to act together.
But the results were far from promising.
All ten slayers were trapped inside the mountain.
This led Ubuyashiki to suspect that the leader of the demon group might be a member of the Twelve Kizuki.
Okane Kichiro happened to be stationed relatively close to the area, so headquarters urgently redeployed him. And not just him—Kagaya had even sent two Hashira to reinforce this mission.
Before Okane Kichiro arrived, Tanjiro's group had already received orders to head toward Natagumo Mountain as well, though their location had been farther away, preventing them from joining the earlier squads.
"Is this the place?"
Okane Kichiro stared at the towering mountain covered in dense forest. Without hesitation, he dashed straight inside.
It didn't take long for him to notice something wrong.
The forest was crawling with grotesque spiders. Thick, sticky threads hung between trees like ghostly curtains. No wonder the area was so sparsely populated—just looking at these webs was enough to drive ordinary people away.
Deep within the forest, a voluptuous female demon with long white hair gently plucked at the threads between her fingers. Her cold eyes shifted.
"Another prey walking right into the web?"
Elsewhere, Tanjiro and Inosuke had already discovered one surviving member from the earlier squad. From him, they learned what had happened.
The ten members had suddenly begun killing each other like puppets.
In the original story, these ten were mere cannon fodder, but in reality, they were ranked above Tanjiro and his group—far from weak.
Ordinarily, ten slayers working together should have no trouble defeating most Blood Demon Art users.
As they spoke, a rustling sound echoed through the forest—as if countless creatures were crawling across leaves.
Murata, the surviving slayer, shuddered and quickly warned them:
"That sound… It's that sound! After we heard it, everyone started slaughtering each other!"
Right after he spoke, several mind-controlled slayers emerged from the trees, their faces twisted in agony, moving like puppets on invisible strings.
Before Tanjiro could react, the controlled slayers charged at them.
Tanjiro hesitated—these were fellow slayers, not demons. He couldn't bring himself to cut them down, leaving him on the defensive.
"It's the threads! They're being controlled by spider threads!"
The moment a pair of spiders crawled onto his left hand, Tanjiro felt his arm freeze. His expression sharpened. Working with Inosuke, he severed the visible threads controlling the slayers.
However, cutting the threads didn't remove the spiders.
Even after breaking free, the victims would fall under control again.
Realizing this, Tanjiro understood the only solution: find the demon controlling them.
But his sense of smell—normally his greatest asset—was being disrupted by a strange scent. He couldn't pinpoint the demon's location at all.
As they discussed what to do, a white-haired young demon descended from the webs overhead, staring down coldly.
"Don't disturb the peace of our family."
"Mother will kill you all soon."
Inosuke, hot-headed as always, ignored everything else. He stepped on a controlled slayer's back, leapt up, and swung both blades—only to miss completely.
The demon boy drifted away effortlessly along the threads.
"That child isn't the one controlling the threads!" Tanjiro shouted, stopping Inosuke.
Finding the puppeteer was the top priority.
"Ohhh, shut up already, Forehead Boy!"
Enraged, Inosuke slammed his blades into the ground. The grudge from losing to Tanjiro's headbutt clearly still haunted him.
"Beast Breathing, Seventh Fang—Spatial Awareness!"
Unlike other forms, Beast Breathing was something Inosuke himself created, derived from the Wind Breathing style. By using his full body to sense subtle vibrations in the air, he mapped his surroundings like a living sonar.
In moments, the entire forest unfolded within his mind.
Then
"Found it! Wait—there's someone else! A super strong aura!"
Inosuke froze.
"What do you mean!?"
Suddenly, every puppet slayer's threads snapped at once. All of them collapsed.
"What… what's happening!?"
Murata held the limp body of a teammate, completely bewildered.
"The demon's aura disappeared—it got killed! Someone cut it down! They're incredibly strong!"
Inosuke's eyes sparkled with excitement.
"Our ally? That's great!"
Tanjiro immediately moved to check the injured.
A few minutes earlier
Tiny spiders had silently crawled onto Okane Kichiro's shoulder. They were about to spit their threads when he casually pinched them between his fingers. A gentle squeeze—gone.
"Blood Demon Art, huh?"
Okane Kichiro saw right through their nature instantly.
These little things were dangerous: their silk could manipulate nerves. Even he would be controlled if caught off guard.
No matter how strong he was, he was still human.
No wonder so many squads had failed. In this dark, web-infested forest, who would notice a tiny spider on their body?
But to Okane Kichiro, the threads themselves revealed a weakness.
Each strand was infused with demonic scent.
And all threads would ultimately lead back to the puppeteer.
With Transparent World, he could see them clearly—the convergence of all threads, the precise point where the demon hid.
He rushed in immediately. If he was too slow, Tanjiro might defeat her first—and as someone who also used Water Breathing, there was no way he'd let Tanjiro claim the "Water Surface Slash – Decapitation" achievement before him.
By the time the female demon realized danger was near, it was already too late.
"How did you find me!?"
Panic filled her eyes. All her power lay in her threads—her close-quarters abilities were nonexistent.
"Well… since you look somewhat decent, I'll try to be gentle."
Okane Kichiro drew his blade and dashed forward.
This demon was still controlling several slayers—he had to finish it quickly.
"What are you babbling abou—"
"Water Breathing, First Form—Water Surface Slash."
Okane Kichiro wasn't gentle after all.
He wasn't about to show mercy to a demon who had murdered so many.