The peaceful facade of the valley had begun to fracture. In the local teahouses and bustling marketplaces of the nearby town, the whispers were no longer about the weather or the harvest. They were about the "Mountain Thunder."
Rumors of thunderous gunfire echoing from the deep cedar forests in the dead of night had spread like wildfire. To the common folk, it was a mystery—a sudden, violent cacophony in a place where only hunters and herb-gatherers dared to tread. But to those who walked the path of the sword, the sound of gunpowder in the Taisho era was a signal of something far more deliberate.
Kanae Kocho, the Flower Hashira, arrived in the region under the pale light of a waning moon. Her initial mission was clear: a Lower Moon demon had been sighted moving through these mountains, a predator of high caliber that the local Slayers couldn't handle.
Yet, as she stepped into the forest, something was profoundly wrong.
"The air is... quiet," Kanae whispered, her hand resting lightly on the hilt of her Nichirin sword.
She moved through the brush with the grace of a falling petal, her keen senses searching for the foul, suffocating scent of a demon. She found it—but it was hollow. She arrived at an empty clearing where the stench of a powerful demon was thick enough to choke a normal man, yet there was no body. No blood. Only a patch of scorched earth and a strange, corrosive sludge that hissed as it ate into the roots of an old cedar tree.
"No demon activity, but the scent remains," she mused, kneeling to inspect the site. "Someone has already been here. And they didn't use a sword."
She stood up, her violet eyes narrowing. The rumors of the "gunfire" now took on a tactical significance. If a person was taking down demons of this level without the Demon Slayer Corps, they were either a rogue element or a miracle.
Kanae closed her eyes, focusing her breathing. She could smell the faint, lingering trail of something else—not the rot of a demon, but the sharp, sterile scent of medicinal herbs and a strange, metallic undertone that reminded her of a high-pressure forge.
"Curious," she said, a gentle but determined smile gracing her lips. "A person doing our work, using weapons of lead and iron... and yet, the demons they touch dissolve into nothingness."
Curiosity took a firm hold of the Flower Hashira. She wasn't just here for the Lower Moon anymore. She was here to find the ghost in the white coat. She followed the trail of the scent, moving toward the outskirts of a small village where a certain clinic sat quietly under the shadow of the peaks.
"Let's see who is playing the part of a Savior in these woods," Kanae whispered, her cloak fluttering as she vanished into the trees.
******
The silence of the mountain was shattered not by a blade's whistle, but by a thunderous, mechanical bang that echoed through the ravines.
Kanae Kocho moved like a streak of moonlight toward the source. As she crested a jagged ridge, she looked down into a clearing and froze. Before her was a scene of absolute carnage. A Lower Moon demon stood surrounded by a dozen lesser thralls. But they weren't the hunters tonight; they were the prey.
In the center of the clearing stood a man in a tattered white doctor's coat, his face a mask of cold, military focus.
He raised a strange, black pistol. Bang. A lesser demon's head vanished in a spray of crimson sparks. But it was what happened next that made Kanae's breath hitch in her throat. As the weapon clicked empty, jagged metallic spikes erupted from the handle, pricking deep into the man's palm. He didn't flinch. Instead, the gun seemed to drink from him, the internal chambers glowing with a low, rhythmic red light as it absorbed his blood to chamber the next round.
"He's using his own life as a magazine," Kanae whispered, her violet eyes wide with horror and fascination.
A demon lunged at his flank, claws extended. In a blur of motion, the man drew a heavy surgical knife. With a single, clinical strike, the demon was beheaded, the wound blackening and sizzling with a strange corrosive effect. As the bodies of the lesser demons began to crumble, the man stepped over them, his hand glowing as he performed a swift, predatory Blood Absorption. The remains didn't just ash; they were stripped of their essence, fueled directly into the man's veins.
The Lower Moon, sensing it was no longer the apex predator, shrieked and unleashed a flurry of blood-soaked lashes. The man didn't move like a Slayer; he moved like an elite officer in a trench. He holstered the pistol and unslung a heavy, bone-textured shotgun.
The demon's attacks lashed the air where he had been a second before. He dodged with a sickeningly fast, high-pressure burst of speed. Boom. The shotgun roared, a wide cone of blood-energy shredding the Lower Moon's chest.
Then came the reload.
It was a grotesque mimicry of the mechanics from the Crisol world. The weapon didn't take shells; instead, retractable needles bit into his forearm, drawing a fresh supply of his crimson essence with a wet hiss of steam. The man gritted his teeth, his face paling as his life force fed the iron.
The demon tried to regenerate, but the wound hissed. Before it could scream, the man pressed the twin barrels against the creature's jaw.
Boom.
The Lower Moon's head was erased in a flash of crimson light. As the powerful demon dissolved, the stranger stood over the remains, his palm drawing the last of its rank-heavy blood into himself. He didn't celebrate. He simply picked up a woven basket of herbs, adjusted his coat, and walked back into the darkness of the trees.
Kanae stayed hidden, her heart hammering against her ribs. She had no idea who this man was, but the scent lingering in the clearing was suffocating—it had the reek of a demon, far more concentrated and potent than any she had ever felt. And yet, her intuition as the Flower Hashira told her something different. This wasn't a monster. This was a being of a similar origin, a man who had turned a curse into a localized, tactical miracle.
"Not a demon," she breathed, watching the shadow of the stranger vanish. "But something the world isn't ready for."
She turned away, her mind racing. She had to return to the Demon Slayer Corps. She had to tell the Master about the man who fought with his own blood—the phantom who had turned the mountains into a sacrificial ground.