The Underworld stood on the precipice of war.
The Old Satan Faction and the Anti-Satan Faction were preparing for what would become known as the Devil Civil War, a conflict both sides believed would determine the very future of their race. Total annihilation of the enemy was the only path forward, or so each faction was convinced.
Most Devils understood which side truly carried the burden of dreams and progress, and which clung desperately to the antiquated ideologies of a bygone era. Yet understanding mattered little when survival demanded the complete elimination of one's opponents.
Grayfia Lucifuge understood this reality better than most. As a member of the Lucifuge Clan, a noble house that had served the original Satan Lucifer for generations, she was duty-bound to fight for the Old Satan Faction. Her family's honor and legacy demanded nothing less.
What the current Grayfia didn't know was that the Anti-Satan Faction would eventually produce four Devils whose power exceeded all expectations: Sirzechs Gremory, Ajuka Astaroth, Serafall Sitri, and Falbium Glasya-Labolas. When those four rose to prominence, the war's outcome would become inevitable.
But that was a future she couldn't yet see.
For now, young Grayfia Lucifuge devoted herself entirely to the faction she believed she owed her loyalty. By human standards, she was only thirteen or fourteen years old, far too young for the battlefield that awaited her.
Today, she had come to her favorite training spot: a secluded waterfall deep in the Underworld's wilderness.
Her exceptional magical talent had manifested early, granting her the ability to commune with the ambient demonic energy flowing through the atmosphere. True mastery of magic required more than raw power; one needed the sensitivity to perceive and manipulate the energy saturating the world itself.
"Hm?"
Something felt wrong.
"There's... more mist than usual today," she murmured, silver-gray eyes narrowing as she surveyed the familiar landscape.
The waterfall looked the same as always, yet the fog clinging to its base seemed thicker, more impenetrable. When she extended her senses, they met unexpected resistance, as though something within the mist actively deflected her perception.
"Since when does the Underworld have mist like this?"
She confirmed visually that everything appeared normal, then dismissed her concerns. Whatever caused the anomaly, it didn't seem dangerous.
With practiced grace, Grayfia let her clothes slip to the ground and stepped into the crystalline pool. The cool water embraced her as she submerged herself completely.
A sigh of contentment escaped her lips.
In this state of perfect stillness, she could almost hear it, the whisper of magic, like tiny voices carried on currents of power. The sensation was faint, almost imperceptible, but unmistakably present.
This is unprecedented, she realized with growing excitement. If I can grasp this opportunity, I might advance to the pinnacle of Ultimate-Class!
Her heart's desires remained conflicted. Did she truly want to help the Old Satan Faction she theoretically owed loyalty to? Or did she secretly sympathize with the reformists who seemed to represent justice and progress?
Either way, she decided, strength comes first. Only the powerful have the luxury of choice.
With that resolve, Grayfia began her meditation.
The area was far different from what she remembered.
Hidden above the waterfall, concealed by the unnatural fog, sat a small house, cozy and elegantly designed despite its modest size.
Outside this dwelling, beneath a sun umbrella, a black-haired young man and a silver-haired woman sat across from each other at a small table. Behind them stood a black-haired maid with an attentive but serene expression.
The young man withdrew his gaze from the pool below and moved a black king piece across the chess board.
"Checkmate."
His smile was faint but genuine, a dimmed radiance visible only to his two companions.
The silver-haired beauty across from him frowned delicately. No matter how hard she tried, she simply couldn't defeat this man at chess.
"I concede," Grayfia said, stretching languidly in a display of casual grace she would never permit herself while on duty. Here, away from her role as the Strongest Queen, she could simply be herself.
Splash.
The soft sound of pouring liquid drew their attention as the black-haired maid stepped forward, offering them fresh cups of coffee.
"Congratulations on your victory, Master," she said, her lips curving into a subtle smile.
"Naturally, Nyx. I've never lost," Takeyo replied, accepting the cup.
Grayfia knew his true capabilities. Had he held back even slightly, it would have been an insult to her intelligence. She appreciated that he always gave her his best.
The black-haired maid, Nyx, the Primordial Goddess of Night from Greek mythology, had undergone an extended period of... education under Kurimo's guidance. After considerable effort, she had finally been brought to heel.
Takeyo's sign-in had completed shortly afterward.
[Ding!]
[Congratulations to the host for completing the plot check-in! Sign-in level: Diamond!]
[Sign-in plot: The Surrender of the Night!]
[Plot: The Goddess of Night brings her dragon-suppressor to challenge you, intending to make you submit as her subordinate. How could such a thing be permitted? Obviously, it should be reversed! Conquer Nyx, the Goddess of the Night!]
[Congratulations to the host for receiving the reward: World-Class Item, Final Judgment: Wheel of the Righteous God & Heaven of the Sinful God!]
[Final Judgment, Wheel of the Righteous God & Heaven of the Sinful God: The Wheel of the Righteous God can exert devastating effects on any target whose karma value is negative. Its range can encompass an entire world.
In other words, this item is a world-class area-of-effect ability, directly affecting all opponents with negative karma.
The Heaven of the Sinful God operates on the inverse principle, targeting those with positive karma values with equally devastating effect.
These are the core powers of the God of Judgment!]
After obtaining this seemingly powerful but currently situational item, Takeyo had formally assigned the conquered Goddess of Night her new role as a maid.
Following an intensive training regimen overseen by Grayfia herself, Nyx had officially debuted in her new position.
"This is why you asked me to build a house here, isn't it?" Takeyo gestured toward the pool below.
A silver-haired girl was meditating at the bottom of the pool, her hair drifting like pale silk in the gentle current. Despite her youth, she radiated the same composed elegance that defined her older self.
This was Grayfia, the young Grayfia from centuries past.
"Perhaps," the present Grayfia replied, her eyes soft with an emotion Takeyo couldn't quite name. "Call it fate."
She had understood many things when she'd witnessed Takeyo summon and manipulate the formations of Heaven and the Underworld. After that revelation, following her own instincts, she had asked him to "bombard the nearest time node."
Through the Corridor of the Fairies, Takeyo had carried them both back to this precise moment in history.
To the turning point that would change her destiny forever.
"Stop staring," Grayfia chided, rolling her eyes at him. "What's so fascinating?"
"Ahem..." Takeyo coughed lightly. "She's still you, after all."
Yet he couldn't deny that the youthful Grayfia possessed a charm entirely distinct from her mature counterpart, the vitality of innocence mixed with untapped potential.
When he'd sensed young Grayfia's arrival, he'd finally understood why the older Grayfia had requested this location.
So this is how causality completes its loop.
Using the Black Sky Krishna incarnation to observe Grayfia's past, Takeyo had already glimpsed fragments of her fate. Unlike the original timeline, this Grayfia had never participated in the climactic battles between the Anti-Satan Faction and the Old Satan Faction.
During that famous war, Grayfia Lucifuge had simply... vanished.
When he'd tried to determine what the disappeared Grayfia had been doing during those missing years, he'd caught a glimpse of someone looking back at him, his own reflection, staring from across the river of time.
In that moment, everything had clicked into place.
So when Grayfia asked him to use his ability to bombard the nearest temporal coordinate, he hadn't hesitated.
Events were unfolding exactly as he'd predicted.
Following Grayfia's suggestion, he'd constructed this small house and used his power to gather concealing mist around it. The fog interfered with perception, ensuring no one could approach unless they were intimately familiar with the area, as familiar as Grayfia herself.
Takeyo had welcomed the arrangement. He'd recently pushed himself to the limit using his Origin Form, and now needed time to recover. If that recovery happened while traveling through time, all the better.
Last time, healing had taken over two months. This time might take even longer.
At least here, I can recuperate in peace.
"Ahem..."
Takeyo's thoughts were interrupted by another coughing fit, golden blood staining his lips.
"Honestly..." Grayfia sighed, but her hands were already moving, dabbing at the divine ichor with practiced efficiency. Something about his vulnerability seemed to trigger her caretaker instincts.
"So tell me," Takeyo said, meeting her gaze. "What role should I play in your heart?"
After traveling through time, he finally understood why Grayfia had always watched him with such complicated eyes. She had known him for far longer than he'd realized, and clearly, things had happened between them.
That explained her jealousy when she'd learned of his relationship with Rias. The pieces finally fit together.
Grayfia was silent for several long seconds.
"Probably..." she finally said, her voice barely above a whisper, "my Master... and the person I've always yearned for."
"Is that so?"
Takeyo's gaze drifted back to the silver-haired girl in the pool below, a knowing smile tugging at his lips.
Beneath the waterfall, young Grayfia felt her power surge.
The breakthrough she'd been striving for had finally arrived, Ultimate-Class, at the very pinnacle!
She released a quiet sigh of satisfaction as she opened her eyes. Silver-gray irises gleamed with barely contained excitement.
Finally. A breakthrough.
Despite the achievement, she didn't erupt from the water in some dramatic display of power. This was her treasured training ground; she refused to damage it with unnecessary theatrics.
Rising gracefully from the pool, she made her way toward where she'd left her clothes.
Then she heard it, voices that shouldn't exist.
"Vina? This dragon meat is excellent. Would you like some more?"
A young man's voice, warm and resonant, reached her ears.
The moment she heard it, Grayfia felt something shift in her chest. It was as though sunlight had suddenly pierced through storm clouds, illuminating places within her heart she hadn't known existed. A sensation of clarity, of cleansing warmth, washed through her very soul.
What... what is this feeling?
She wanted to hear more. She needed to hear more.
Her first instinct wasn't to question why strangers were at her secret training spot. It wasn't to grab her clothes. Instead, her only thought was: I have to see the person behind that voice.
"Master Takeyo, you should eat more vegetables. It's better for your health."
Young Grayfia's eyes narrowed. A female voice, and somehow familiar?
Where have I heard that before?
She couldn't place it.
Are they... having a barbecue?
The absurdity of the situation struck her. Others were grilling dragon meat beside the pool where she practiced. At her waterfall.
"Hey! Why are you just standing there? Do you have some kind of special hobby?"
The question was clearly directed at her.
Blood rushed to young Grayfia's face faster than she'd ever experienced. Her entire complexion turned crimson.
Someone saw me!
A man saw me!
That single thought propelled her into motion. Moving faster than she ever had in her life, she snatched up her clothes and fled, still completely naked.
Some might call it streaking.
Only after she'd put considerable distance between herself and the waterfall did she finally manage to dress.
Fully clothed at last, young Grayfia took a deep breath, gathering the courage to actually face whoever had witnessed her mortifying display.
Whoever he is... I have to know.