Mist hung heavy above the twin pools of the hot spring resort. Steam drifted like veils across the lantern-lit courtyard, thick enough to blur the bamboo walls that separated the men's side from the women's. Every few breaths, the silence broke with the gentle splash of water. Someone had entered the bath.
Yukishiro disrobed without hesitation, keeping only a pair of plain white swimming trunks. His bare chest and shoulders caught the glow of the lanterns—broad for his age, marred by scars.
He carried his silver Nichirin Blade to the edge of the pool, setting it on a flat stone where his hand could reach it in an instant. Then, without a word, he stepped into the water.
The heat enveloped him. Muscles that had been taut for days loosened slightly under the spring's warmth, though his eyes remained sharp.
Fukada followed a beat later.
He had intended to keep his composure, but the moment his eyes landed on Yukishiro's body, he froze. His breath caught.
The youth could be no older than eighteen or nineteen, yet his skin bore dozens of old wounds. Jagged scars crisscrossed his chest, arms, even his back.
They were not the marks of clumsy accidents. They were battle wounds—evidence of years of fighting, of survival against horrors Fukada could barely imagine.
A tremor passed through the man.
"This boy… what kind of life has he lived?" He looked at the distant, stoic face, and a chill swept through him. "No wonder he acts like a man carved from stone. He's already walked through hell."
Yukishiro waded to the far side of the men's pool, settling himself at the spot closest to the bamboo partition. His blade rested behind him on the stone ledge.
The water rose up to his chest, concealing most of his frame, but the sharp stillness of his presence seemed to cut through the steam itself.
Fukada, uneasy, sat down a little distance away. He had never felt so small in another's shadow.
"Yukishiro? Are you there?"
The voice floated from the women's pool. Mitsuri's tone was gentle but hesitant, softened by the mist and the splash of water.
"Mm." Yukishiro gave the faintest of nods, not even turning his head.
The simple sound seemed to reassure her.
On the other side of the bamboo, Mitsuri smiled, her cheeks warm from the water and the shyness that had settled on her ever since she realized how close they were, separated only by a thin fence.
The hot spring's warmth soaked into her body, easing the fatigue of endless travel and missions. She exhaled, watching the steam curl upward. "It really does feel magical. I haven't felt this light in weeks."
But even as comfort spread through her limbs, tension remained in the air. The "murderer," as the townsfolk called it, did not appear.
Hours passed.
The three of them remained on edge through the first half of the night.
Then, as the moon reached its zenith, Yukishiro sank deeper into his own method of vigilance.
He slowed his breathing, steady and deliberate, entering a state that looked like slumber. His consciousness drifted inward, but his senses stretched outward, every ripple of heat and cold recorded. It was meditation, not carelessness.
Even in this trance, the faintest shift in temperature would snap him awake blade in hand.
Fukada, however, could not know this. Watching the young Demon Slayer's stillness, his heart sank. "He's… asleep? At a time like this?!"
Disbelief turned quickly to anger.
"Are they really so inexperienced? Rookies, both of them! And I trusted them?" His thoughts spun with resentment and fear.
More than once he opened his mouth to wake Yukishiro, but shame held him back. The boy's presence was too heavy, his aura too sharp, even in apparent sleep.
Fukada clenched his fists under the water, deciding he would wait until the so-called murderer appeared before shaking him awake.
The night passed uneventfully. When dawn crept into the sky, Mitsuri emerged from the women's pool glowing with energy, her steps light.
Yukishiro followed, expression calm, his body refreshed.
Fukada stumbled behind them, hollow-eyed, his head throbbing from a sleepless night.
"They're just lucky," he muttered under his breath.
…
Three nights passed in this manner.
Each time, Fukada endured the baths with them, tense as a bowstring, convinced doom would strike. Each time, nothing happened. His doubts about Yukishiro grew, even as he feared the boy too much to confront him directly.
Instead, he pulled Mitsuri aside when he could.
"Tell him," Fukada begged her. "Tell him not to sleep at night. The enemy could come at any moment! You have to stay awake, both of you."
Mitsuri tilted her head, blinking at him. "Oh, you mean Yukishiro's meditation? That's not sleeping. It's… how Demon Slayers rest without lowering their guard."
Fukada stared, baffled. "Meditation? Resting while awake?"
Her sincerity made it impossible to argue further. He shook his head, helpless. "I don't understand them. I'm just a small man. Better to keep following and pray I survive this."
So he did. For three long, sleepless nights.
…
On the fourth night, everything changed.
As soon as they crossed the resort's wide hall and stepped into the backyard, Yukishiro froze mid-step.
Steam billowed from the pools as usual, curling in the lantern glow, but beneath the haze lurked something else—two presences.
Cold. Faint, but undeniable.
His pupils narrowed. "Demons."
He could feel them clearly, their signatures hidden in the pools—one in the men's side, one in the women's. It explained everything.
The missing girls, the silent vanishings. These demons had concealed themselves within the water itself.
His hand tightened on his hilt. A surge of icy breath escaped him, rolling off his body like a tide. Frost bloomed across the ground within a meter of him, water vapor crystallizing into shards of ice that clattered onto the stones.
The steam shivered.
From the men's pool, a ripple spread, the water trembling as though something had shifted beneath the surface.
Fukada flinched, his teeth chattering as the air froze.
"Th–this boy…!" His heart pounded. At last, he believed. The cold emanating from Yukishiro was inhuman, overwhelming.
Yet strangely, the demon did not attack.
The ripple subsided.
The water stilled again.
Yukishiro narrowed his eyes. "They're… staying put?"
It made no sense. In his experience, demons struck the moment prey drew near. But these two… they sat quietly, their presence chilling yet eerily passive.
Mitsuri gripped the hilt of her blade, scanning the mist. "What's wrong? Do you sense something?" To her eyes, there was nothing—only steam and water.
"Quiet," Yukishiro murmured, easing his hand away from the hilt. Forcing the frost back into stillness, he let the warmth of the hot spring return.
With the others watching, puzzled, he moved deliberately toward the men's locker room. There, he shed his clothes again and re-entered the men's pool, lowering himself into the same spot as before.
But his gaze fixed unerringly on the far corner of the water.
Mitsuri and Fukada joined him in turn, though Fukada hugged the far edge, shivering from both fear and cold.
Time crawled forward.
The two demons remained silent. Hours passed without incident.
"Why aren't they moving?" Yukishiro thought, his eyes shut as he slipped into meditative stillness once more. "Are they observing us? Testing us? Or are they simply waiting…?"
But then, just before dawn, the atmosphere shifted.
A scent threaded through the mist, faint but insidious.
Sweet at first, almost like flowers, but beneath it lay something sharp and cloying. Yukishiro inhaled once—and his head swam.
His body weakened at once. Limbs heavy, strength leaking from his veins.
"No…!" His mind flared in alarm. "It's a trap. This scent—it's a toxin!"
He reached for his Nichirin Blade, but his arm faltered.
His grip trembled, unable to lift the weapon even an inch.
Beside him, Fukada slumped unconscious against the rocks, his head lolling.
A surge of dread shot through Yukishiro. "Worse than Fujikasane Mountain… At least then, I could fight back. Now… I can't even move."
He forced his body upright with raw will, clutching at the stones of the pool's edge. His breathing grew ragged as he tried to summon his cold techniques to burn through the haze in his mind. Ice crackled faintly across the stones—but the effect was pitiful, the poison too strong.
Ripples disturbed the surface. Something stirred within the men's pool.
Yukishiro braced, ready for the strike.
But instead of an attack, he heard water spill. The unseen creature rose, footsteps wet against the stone tiles. Droplets pattered, forming a line of damp prints that trailed across the ground… away from him.
Through the mist, the prints led toward the lobby. Then silence.
The demon was gone.
Yukishiro's chest heaved, fury and frustration burning hotter than the toxin that weighed him down. He had let the chance slip through his fingers.
Even after his strength returned with the light of morning, the demons did not show themselves again.
But their presence lingered in the pools, chilling and patient, like hunters who had all the time in the world.