The wheels of the Mugen Train roared against the rails, a metallic lullaby echoing through the night. Smoke curled from the engine as the countryside blurred past in streaks of darkness and moonlight. Beneath this still veneer, evil stirred.
Hidden above the fifth carriage, cloaked in a veil of divine silence and perception-dampening enchantments, Tharion crouched like a gargoyle. His eyes, forged by a thousand lifetimes of sorrow and resolve, scanned the length of the train. The burden of time slowed for no one—not even a Watcher chosen by the gods.
Tonight, he would not fail.
He had arrived hours earlier, stepping into this world with the gods' directive etched into his soul. Save Rengoku Kyojuro, the Flame Hashira, from the fate that awaited him. To do that, he had borrowed—no, silently borrowed—a Nichirin blade forged by the Swordsmith Village chief himself, one able to withstand the full breadth of the Sun Breathing forms. Slung across his back now, it hummed with anticipation.
Inside the train, Kyojuro sat upright in his seat, arms crossed, a tranquil titan unaware of the storm to come. His breath was calm, steady. His presence, undeniable. There was something magnetic about him—a brightness that defied darkness itself.
From his perch, Tharion watched the others:
Tanjiro Kamado, the kind-hearted boy with a tragic past, asleep, dreaming of his family.
Inosuke Hashibira, the wild one, twitching even in dreams, blade across his chest.
Zenitsu Agatsuma, clinging to the seat's edge even as he slept, mumbling about Nezuko.
And Nezuko, quiet inside her box, aware. Watching.
Tharion's gaze hardened. Time was close. Enmu, the Lower One demon of Muzan's Twelve Kizuki, was already at play, ensnaring the passengers in dreams to lull them before feeding.
With precise steps and unheard breath, Tharion slipped toward the rear of the train. Reaching under the sixth carriage, he summoned a rune—a binding sigil of divine command. With a single whispered word, he cut the last two wagons loose, ensuring that when chaos broke out, the civilians within those cars would be far from danger.
He moved back quickly, rejoining the upper frame of the fourth carriage. Now was not his time to shine. His role was to watch. Guard. Guide. And strike when the scales tipped toward tragedy.
And they would.
The dream began to unravel.
Rengoku's brow twitched. His breath caught. He knew.
In the world of illusions, he had been reliving his past—his mother's final words echoing in his ears, reminding him of the strength of the Flame and the duty of a protector. But something shifted.
Nezuko, outside the dreams, stirred first. Emerging from her box, she sensed the disturbance and, using her blood demon art, burned the dream spell from Tanjiro.
Crack.
Tanjiro's eyes shot open.
"Rengoku-san…!"
In a cascade of shouts and motion, Zenitsu and Inosuke snapped awake—Inosuke swinging wildly before realizing where he was, Zenitsu crying out before steadying himself.
The air shifted. A grotesque hum rolled across the carriages.
Enmu had revealed himself.
The Lower Rank demon grinned, his face stitched with insanity and madness. Flesh melded with steel, his body fused with the very train, hundreds of eyes and mouths stretching across the walls like a living nightmare.
Screams echoed from the passengers. The train had become a demon itself.
Rengoku stood, calm yet fierce, drawing his katana."Protect the passengers. We split up and guard each car!"
Tanjiro nodded. "Yes!"
Inosuke laughed wildly. "This is it! A demon train? That's awesome!"
Zenitsu trembled, but drew his sword nonetheless. "Nezuko-chan… please be safe…"
Above them, unseen by all, Tharion remained. The blade on his back pulsed, but he waited. The Lower One would fall by their hands. It was the Upper Rank that would require him.
And soon… it would arrive.