The Holy Grail War is a battle over the "Holy Grail," an artifact said to grant the wishes of its possessor.
The Grail itself originates from the legend of Christ and is a miracle among miracles.
And in Fuyuki City, at this very moment, a secret Holy Grail War is being waged. It should have been a war to fight for miracles, to fulfill one's own will and convictions.
That door leading to the dreamland of all magi was, for the first time in this war that should have been another repetition of tragedy, foreseen by the two Counter Forces—Alaya, humanity's will to avert all ruinous futures, and Gaia, the planet's will praying for the extension of life—as opening toward a dreadful conclusion.
Normally, through that door, Heroic Spirits formed from the heroes, champions, kings, and gods of history would be summoned to this land, drawn by their powerful wishes resonating with the Grail. They were meant to fight upon this stage for the fates they bore, the paths they pursued, and the futures they struggled for, spending every last drop of mana.
But today, everything had changed.
The two Counter Forces sensed an unprecedented threat. This was not simply against "human order," but an all-encompassing annihilation that granted absolute equality to the destruction of all things.
The two Counter Forces could not allow such a pitiful conclusion to arrive. Therefore—they intervened directly in the contest.
Through communion with the Root and by granting promises to the strongest Heroic Spirits of this world, the Counter Forces forcibly twisted the laws, binding the sprout of this menace into this Holy Grail War.
To ensure this malice could be eradicated, the Counter Forces even poured in the majority of their stored power into this battle.
Yet this [Absolute Annihilation of Equality], origin unknown, was hidden far too deeply. The Counter Forces could not locate its position, discern its form, nor even perceive the manner of its existence.
That meant—it was entirely possible that the seven powerful Servants summoned would become possessed by this 'malice.'
But the Counter Forces could no longer afford to consider finer details. In the end, they decided—rely on miracles born of overwhelming force.
As long as unprecedentedly powerful Heroic Spirits were summoned, surely this terrifying crisis could be quelled.
Such was their belief.
...
Meanwhile, in a small inn within Fuyuki City—
"It's been such a long, long time since I've felt a world this peaceful, even if it's just an illusion for a moment."
Satsuki, dressed in a black kimono, stretched out languidly. Her appearance had not changed much—still the pair of Ōtsutsuki earrings, still the gold-trimmed black robe embroidered with five-clawed dragons and twisted Sanskrit. She had retracted the Vipralopa Halo, while her smooth, long hair spilled freely down her back. A faint lotus fragrance lingered in the air.
She sat before a neatly arranged single bed, one leg crossed over the other as the fabric parted slightly at her thigh. Her eyes held radiant curiosity as she watched the electronic device before her, black pupils gleaming when the once-dark screen lit up and settled on the colored image of a television broadcast.
Electronics—since her rebirth, it had been some time since she last encountered such things of technical ingenuity.
"Hey, this is the Holy Grail War. Is it really okay for you to be this relaxed?"
The speaker was another woman in the room, around twenty years of age, with a face beautiful and flawless like a doll's. Ruby-like eyes, long silver hair shining like snow. She wore a white off-shoulder camisole top, a long skirt, and white stockings.
Though she bore the air of an exalted princess, her expression carried a constant sense of contradiction. She pressed her hand to her head in slight irritation as she looked at the girl who showed endless curiosity toward everything. "And besides, such crude mechanisms aren't as reliable as you think."
This girl had dragged her out from the depths of darkness without so much as asking, then without warning forced her into this female form and became her Master. Just what kind of existence was this girl before her? What purpose did she hold? Even now, Angra Mainyu could not understand any of it—and naturally, she had no intention of showing a pleasant face to someone acting so presumptuously.
It was not her first time in a Holy Grail War. Once before, she had been summoned as a Heroic Spirit, her class being the one that wandered beyond the seven: Avenger. Though its legend was astonishing, being none other than the conceptual "All the World's Evil," for various reasons, in that war she had lasted only four days before being defeated.
Shame. An inescapable shame.
"I've already heard your explanation about the Holy Grail War. You really care about winning and losing, don't you?"
Satsuki, eyes still fixed on the wildlife program playing on the television, answered casually: "Anything that exists will eventually be destroyed. As long as humans have desires, they will fall into corruption. All things follow the same law—where there is life, there is death. So-called victory and defeat are nothing more than fleeting perceptions."
At that point, her desire for long arguments vanished, and she focused entirely on the television. "Though I don't really have the right to lecture you. I suppose I also care somewhat about victory and defeat. But taking battles with those Heroic Spirits too seriously would only make me seem petty."
"Tch. How grand of you, Saver." Angra Mainyu spat half a line, then turned her face away, falling into a daze.
But Satsuki had no intention of trading further words. Instead, she fell into thought.
She could not truly understand why she had appeared here. Was it because the system had temporarily lost connection? Or was it because her Demon Buddha true body had gained awareness during the crossing?
She had no clues. More importantly, she was unfamiliar with this world.
As the closing music of the program sounded, Angra Mainyu's stomach growled loudly—gururu~—an embarrassing protest. She froze, stunned. Hunger… it had been far too long since she last felt such a thing.
Just as she was about to get up and buy food, Satsuki stood up first.
"As your temporary Master, it's better if you stay here. If anything happens, I'll return immediately."
The girl in the black kimono slid the wooden door open and stepped out with a cold expression, leaving Angra Mainyu behind to stare awkwardly at her own body.
Walking slowly through the streets in the invisible state of a spirit form, the girl's face was entirely different from what it had been indoors. She had already returned to her familiar aloofness and reason.
"Is it because of these familiar surroundings that memories of my past life feel so vivid?"
She muttered to herself. Speaking to a stranger—such was never her style. Or was it because her body had changed? She raised her wrist, her black eyes gazing at the slowly rotating bracelet inlaid with three different-colored gems.
It was the "Three Divine Kings' Sacred Wheel," constructed by the three kings with their authority before crossing worlds.
As a Noble Phantasm surpassing the level of the Grail's restrictions, its abilities were tyrannical: [Wheel of Yama's Extinction], [Wheel of the Spirit King's Fate], and [Wheel of Brahma's Creation].
They respectively represented the god of destruction embodying [Instant Death], the god of maintenance wielding [Status Manipulation], and the god of creation commanding [Energy Control].
Even one of these alone would be enough to reach EX rank. Now, with all three combined, it was terrifying beyond measure.
"Truly a frightening Noble Phantasm."
Satsuki lightly brushed her fingers over the bracelet.
But the actual results were still unclear. After all, in this world, her energy had not yet fully converted. Driving this treasure would require immense mana.
In her prime, it would have been nothing. But the difference in the Root meant she needed time to restore her strength, and the overexertion during her transfer had left her suffering backlash from time and space. Together, these left her far from her Demon Buddha peak. Manipulating the End-Law Halo was her limit for now.
Still, in this world, she believed she was unmatched.
"The system can't respond for now due to energy output overload. Fortunately, the Giant Tenseigan can still send me energy through the channel."
As she thought this, her eyes shifted into golden Tenseigan.
She slowly opened her senses, beginning to attune to the natural energy of this world.
A moment later, she opened her eyes with a hint of disappointment. The energy flowing here was of another kind, based on spirit veins, seemingly connected to the Grail's power, yet quite different from the natural energy of the shinobi world.
It seemed [Sage Mode] could not be easily used in this world without fully adapting to this energy.
"This world appears to lack natural energy suitable for extracting senjutsu chakra. Still, with the Giant Tenseigan's support alone, I need fear no one."
Just then, within her sensory range, she detected a massive surge of magical energy being released.
"Rather than guess, perhaps confirming it through battle would be a better way."