-Prologue-

The Matou Manor stood as a monument to corruption, its once stately halls now reeking of rot and decay. Beneath the ground, where the stench was thickest, lay the darkest heart of the manor—an underground pit writhing with malice. Here, in the damp, suffocating chambers, ancient and grotesque creatures twisted through the soil. These were the worms of the Matou family, living curses that fed on the pain and suffering of their victims. Their wriggling forms, grotesque and foul, filled the room with a nauseating presence.

At the center of this pit, Sakura Matou stood before a glowing magic circle, her body trembling with both fear and fatigue. Her skin was pale, her expression vacant, as she recited the words of the summoning ritual. Every syllable seemed to cost her a piece of herself, as though the darkness of the pit were consuming her from the inside.

In the shadows loomed Zouken Matou, his sunken eyes gleaming with anticipation as the ritual drew to a close. His crooked form seemed almost to blend into the walls of the pit, a creature as ancient and corrupt as the worms that writhed beneath his feet. He watched intently as the circle flared to life, the room filling with the blinding light of summoning.

"Let silver and steel be the essence."
"Let stone and the archduke of contracts be the foundation."
"Let the winds rise, walls of the four cardinal directions."
"Let the three-forked road to the Kingdom cycle."
"Let it be filled. Again. Again. Again."
"Let it be filled fivefold for every turn, simply breaking asunder with every filling."
"I declare, your body shall serve under me, and my fate shall be your sword."
"Submit to the beckoning of the Holy Grail."
"If you heed this call, if you accept my will and reason, then answer me."
"I hereby swear that I shall be all the good in the world."
"That I shall defeat all evil in the world."
"From the seventh heaven, clad in the three great words of power, come forth from the circle of binding…"
"Guardian of the Scales!"

The summoning circle erupted in a flash of light, its radiant energy filling the foul pit with an unnatural glow. The worms recoiled momentarily, retreating from the surge of power that now pulsed through the chamber. And from within the light, a figure began to take shape—a powerful silhouette that stood tall and unwavering.

Narumi Uzumaki, the Immortal Sage, emerged from the summoning circle, her form materializing in full glory. Her blonde hair shone like spun gold, cascading down her back, while her eyes, sharp and piercing blue, surveyed the room with a keen intensity. Her armor gleamed with an ethereal glow, and chakra swirled around her like a living force.

The first thing that struck Narumi wasn't the coldness of the room, but the stench. Her sharp senses picked up on the rot, the foulness of the air thick with the presence of countless worms. They slithered and writhed beneath the earth, their dark, twisted forms pulsing in the shadows like grotesque serpents. Narumi's stomach churned with disgust, her lips curling as she felt the vile creatures crawling just out of sight.

Her chakra flared instinctively, sending a wave of repulsion through the pit, pushing back the oppressive darkness. But it wasn't enough to banish the lingering malice that hung in the air like a fog. Narumi's gaze finally fell on Sakura Matou, her new Master. The girl was barely standing, her body weak and drained from the curse of the worms that infested her very soul.

Pity swelled in Narumi's chest as she stared at Sakura's frail figure. The dark tendrils of the Matou curse clung to the girl, digging into her like parasites. Narumi could sense them, their vile presence crawling through Sakura's body, feeding off her despair. She wanted to reach out, to cleanse the girl of the corruption that plagued her—but she knew it wouldn't be easy. These worms were too deeply rooted.

"This… cruelty," Narumi whispered, her voice barely above a breath. She took a step forward, but before she could offer any comfort to Sakura, a twisted voice cut through the air.

"Who… are you?" Zouken Matou rasped, stepping into the light, his withered form bathed in the glow of the circle. His eyes gleamed with a grotesque delight as he examined Narumi, clearly intrigued by the powerful presence before him.

Narumi turned her gaze to him, her eyes hardening at the sight of the ancient magus. There was no humanity left in him—only malice and rot. Her disgust deepened as she sensed his twisted connection to the worms, the very creatures that had violated Sakura's body and soul. Yet, her voice remained steady, unwavering.

"I am Narumi Uzumaki," she said, her voice carrying both strength and sorrow. "Servant—Rider."

Zouken's grotesque smile widened. He had known many heroes throughout his long life, but none with the weight of the name she bore. The legends of the Immortal Sage, the hero of countless myths and civilizations, had spread across the ages. A hero who had transcended time itself.

"A hero of such renown… delightful," Zouken muttered, his words dripping with satisfaction. "We have summoned a legend, a true legend."

But before Narumi could react, something shifted. The flow of prana connecting her to Sakura flickered, weak and unstable. Narumi felt the connection straining under Sakura's broken state. She could sense the girl's exhaustion, her frail body unable to sustain the enormous energy required to maintain a Servant of Narumi's caliber.

From the doorway, Shinji Matou entered the room, his face twisted into a smug grin. He held a grimoire in his hands—an artifact passed down through the Matou lineage, which Zouken had prepared for this moment. With it, they could forcibly transfer the contract from Sakura to Shinji, ensuring that Narumi would be bound to someone more capable of supplying prana, at least in theory.

"Looks like I'm your Master now, huh?" Shinji's lecherous voice grated on Narumi's ears. His gaze roamed over her form, lingering far too long on her figure, his smirk widening with perverse interest.

Narumi's eyes narrowed, a flicker of disgust passing over her face. She knew instantly the kind of person Shinji was—the kind of man who used power not for noble purposes, but to dominate and degrade. Her body tensed, every fiber of her being revolted by his presence, and her disgust only deepened as she felt the transfer of prana solidify the bond between them.

The grimoire glowed, the ritual complete, and the command seals transferred from Sakura's frail hands to Shinji's outstretched palm. The connection between Narumi and her true Master severed, leaving her feeling weak and incomplete. Shinji, though arrogant, lacked the magical ability to properly supply her with the prana she needed. Her power, already diminished in Rider form, was now stifled even further.

Shinji, oblivious to the gravity of the situation, approached Narumi with an air of entitlement. His eyes glinted with a sickening desire, as though he saw her not as a warrior, but as an object. "You'll obey me now," he said, his voice oozing with satisfaction. "I'm your Master, after all."

Narumi stood still, her fists clenched, her body brimming with restrained anger. She glanced briefly back at Sakura, who had collapsed against the wall, her body too weak to continue. The girl's eyes, half-lidded and filled with pain, stared vacantly into the distance.

Narumi's heart ached for her. This girl… her true Master… had been forced into hell. And now, there was nothing she could do. Her power was bound by the twisted will of the Matou family, her fate tethered to the hands of a lecherous boy who barely understood the war he was about to enter.

"I will free you," Narumi vowed silently, her eyes lingering on Sakura's broken form one last time before she turned her attention back to Shinji. But for now, I am bound.

The Holy Grail War had begun, and Narumi Uzumaki, the Immortal Sage, found herself shackled not by chains, but by fate itself.

"This war," she whispered, her voice filled with quiet resolve, "has only just begun."

-end-

Note: For now, this is just a oneshot.