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Chapter 337: Chapter 333 ~ Cooperation and Origin

The meeting chamber of the Demon Kings was enveloped in a solemn, dignified quiet.

High ceilings arched above, adorned with floating symbols of ancient devil clans, their soft crimson glow reflected against the polished obsidian walls. At the center of the room sat a massive circular table carved from a single slab of white marble veined with streaks of gold—a symbol of unity among the Four Satans.

Sirzechs Lucifer and Ajuka Beelzebub occupied their respective seats, reviewing the last of the dayʼs documents with practiced efficiency. Behind Sirzechs stood Grayfia Lucifuge, ever the picture of poise and formality, her silver hair cascading neatly down her back as she awaited her masterʼs needs. Her presence alone lent the room an air of disciplined serenity.

Two other ornate seats remained empty—those belonging to Serafall Leviathan and Falbium Asmodeus.

The group had concluded their official meeting moments ago, and the absent Demon Kings had already departed: Serafall to resume filming her newest magical girl movie, and Falbium to return to his residence for much-needed rest.

Sirzechs and Ajuka, however, stayed behind to finalize the crucial preparations for the upcoming second Tri-Summit—a monumental event to be hosted at a venue personally prepared by Yuuji.

This summit was expected to shape the political landscape for years to come.

Stacks of neatly arranged documents and files were spread across the marble surface before them.

Many had already been reviewed and signed, but several still awaited completion before the dayʼs end. The atmosphere was calm, almost heavy, disturbed only by the occasional flick of parchment or short exchange of thoughts between the two Demon Kings.

Then—

A faint hum of magic resonated through the room.

Ajuka reached for a slender handheld device at his side, its polished surface engraved with intricate sigils. It was an enchanted communicator—an advanced, sleek version of the [Message] tool, this one crafted and distributed exclusively by Linked Horizons. By injecting a trace of magic and focusing on the intended recipient, it allowed instantaneous conversation across any distance.

It was the latest model—naturally, Ajuka had been one of the first to acquire it.

Sirzechs glanced up. 

”What is it?”

Ajuka didnʼt answer immediately. His hand continued writing as he activated the device, multitasking with ease. But as soon as the voice on the other end began speaking, his pen halted mid-stroke.

”...Really? Are you certain?”

His normally composed tone sharpened with rising excitement. His eyes widened—if only slightly, but enough for Sirzechs and Grayfia to notice. For someone as controlled and intellectually disciplined as Ajuka Beelzebub, this reaction was nothing short of extraordinary.

”Yes. Set up the meeting as soon as possible. No—adjust to their schedule. Cancel whatever I have at that time. Good. Notify me once everything is arranged. …On second thought, Iʼll head there personally.”

He ended the call swiftly, slipped the device back into his coat, and immediately began signing the remaining documents at a noticeably faster pace. A smile—small but unmistakably pleased—lifted the corners of his lips.

Sirzechs raised an eyebrow. 

”What happened? Judging from that reaction, it must be very good news.”

Ajuka exhaled, still wearing that rare expression of triumph.

”One of my subordinates just informed me—Lady Estelle of Linked Horizons has accepted our proposal for joint research. Specifically, the study of origin transformation into pure-blooded devils.”

Sirzechs blinked, momentarily stunned.

Linked Horizons rejecting proposals was the norm; acceptance was the exception.

He knew this painfully well.

In fact, despite his attempts to strengthen trade and diplomatic ties, only a handful of his initiatives had ever been approved.

”…They actually agreed?”

Ajuka nodded, closing the last folder with a satisfying snap..

”With this cooperation, I can finally obtain solid data. Insights. Frameworks for analysis. Even if they provide only fragments, it will be enough to propel our research forward exponentially.”

Grayfiaʼs eyes softened with intrigue.

”Linked Horizons rarely shares internal expertise. This is… unprecedented.”

Ajukaʼs expression grew serious, though excitement still lingered in his tone.

”Linked Horizons is far more than a conglomerate of businesses. Their research divisions surpass even the most advanced laboratories in the supernatural world. Theyʼve pioneered breakthroughs in magical engineering, artifact analysis, catalyst synthesis, and the refinement of rare materials. Their success rate, quality, and innovation outperform every nation and faction combined.”

Sirzechs leaned back, thoughtful.

”And now theyʼve opened the door… even if only slightly.”

”A slight opening,” Ajuka echoed, ”is all I need.”

Sirzechs let out a low chuckle. 

”I suppose the genius of the Underworld has been waiting for this moment.”

Ajuka pushed up his glasses with a glint in his eye.

”For years. Now, at last, we can begin.”

He stood gracefully, gathering the completed documents and preparing to leave.

Sirzechs called out, ”Youʼre heading there immediately?”

”Of course.” Ajukaʼs tone was firm. 

”This may shape the future of devilkind. I cannot afford a delay.”

Grayfia bowed slightly. 

”Safe travels, Lord Beelzebub.”

Ajuka paused at the doorway, offering a rare, genuine smile.

”Thank you. If all goes well… the age of decline for pure-blooded devils may soon come to an end.”

And with that, he stepped out—his footsteps echoing with purpose.

Sirzechs watched him go, a deep exhale slipping past his lips.

Grayfia spoke gently.

”Are you concerned, my lord?”

”Concerned?” He folded his arms. 

”Perhaps a bit, yes... Linked Horizonʼs influence grows deeper and broader with each passing day. And this collaboration… is another step toward a world completely reshaped by them.”

Grayfia lowered her gaze respectfully.

”Change is inevitable. As far as we see, theyʼve shaped it into something better. Theyʼve even thwarted the Old Satan Factionʼs plans in the past without asking us for a favor. But… I do understand your point. Let us hope it leads to peace rather than upheaval.”

Sirzechs nodded slowly.

”Yes. Let us hope.”

--------------------------------X--------------------------------

The decline in population brought about by centuries of devastating war did not afflict the devils alone.

As countless pure-blooded devils perished on the battlefield, a similarly grievous number of angels fell in service to Heaven. And with the angels dying in droves, the ranks of the Fallen also began to wither. After all, without angels to fall from grace, no new fallen angels could be born. The losses were universal, deep, and devastating.

The population crisis was not a mere inconvenience—it was an existential threat that hung over every faction like a sword suspended by a single, fraying thread. 

With fewer citizens came fewer workers to sustain industry, weakening each factionʼs economic and technological foundation. With fewer soldiers came a frightening vulnerability in a world where danger lurked in every shadow.

Thus, for all three factions—Heaven, the Underworld, and the Fallen—the decline of their numbers had become one of the most critical issues of the age.

Pure-blooded devils faced this problem most acutely. Their naturally low birth rate—already a strain in times of peace—became disastrous during the war. And without pure-blooded heirs, their ancient noble houses were at risk of thinning into insignificance. 

The fear was not merely symbolic; bloodlines were foundations of power, authority, and most importantly, magical potential.

Without intervention, the future of devil society was one where the magical potential directly tied to the purity of their bloodline would slowly disappear into the sands of time.

Thus, arranged marriages between noble families were heavily encouraged, if not outright engineered. Riasʼs former arranged engagement with Riser was one such example—an attempt to preserve the pedigree of two ancient houses through forced union.

In response to this crisis, devils devised their greatest socio-magical breakthrough:

the Evil Piece System.

But it was only a partial salvation.

The system allowed devils to reincarnate beings of other races into half-devils—valuable as soldiers and civil servants, but offering no salvation to the problem of dwindling pure-blood lines. In the long term, even the reincarnated population would contribute to the dilution of devil heritage.

The angels, too, would face a similar solution in the future. 

As Yuuji remembered from the events shown in the anime, the devils would later aid Heaven in creating their own counterpart—the Brave Saints System, granting Heaven the ability to reincarnate humans into half-angels. A symbol of peace and cooperation, yes—but a fundamentally flawed system nonetheless.

Reincarnated angels could never become pure-blooded.

Their wings, their grace, their essence—would forever remain incomplete.

Heavenʼs only true method of increasing the number of pure angels was through birth.

And just like the devils, their birth rate was terribly low.

Worse yet, Heavenʼs archaic strictness toward sin was a crippling shackle. Even the faintest stirrings of lust, the simplest flicker of jealousy, the most fleeting shadow of anger—emotions natural to any relationship—could plunge an angel into damnation and turn them into a fallen.

Marriage was not rare. But procreation, extremely. Only true love could survive Heavenʼs laws, but even then, it was still at risk. 

Thus the angels faced a slow, quiet extinction… a fate Heaven itself had no adequate answer for.

But Yuuji did.

Beyond strengthening Heaven through expanding human faith, beyond stabilizing its ancient system, he had begun to form a plan—one far more ambitious, far more revolutionary.

He would ensure the survival of Heavenʼs race not merely by increasing numbers… but by changing the very rules that dictated how angels lived.

One of the methods he envisioned was simple in concept, yet monumental in consequence.

He would adjust the system itself. Rewrite Heavenʼs ancient laws. Free angels from the bondage of involuntary fall.

If the system could be tweaked—carefully, subtly—to redefine what constituted a ”sin” worthy of condemnation, then angels could finally love freely, marry freely, and bring new pure-blooded life into the world without the crippling fear of exile.

It would be one of the greatest miracles Heaven had ever received since the era of the God of the Bible.

And Yuuji was determined to make it happen.

He needed Heaven, the Underworld, and the Grigori—all three pillars of this world—to stand stronger than ever before. Not for politics. Not for balance.

But because he knew what lurked beneath the surface.

Monsters in shadows. Schemes centuries in the making. A rot buried deep in the foundations of the world, waiting for the right moment to swallow everything he cared about.

So Yuuji had to do his best with Heavenʼs System. 

He and the Multiverse Group Chat had already marked the masterminds behind the Old Satan Factino for Death. Both as part of their mission and because they were the centerpiece of calamity in this world, the ones who repeatedly threatened the future Aika, Rias and her peerage deserved to live in.

But even once they were gone… The world would not suddenly become peaceful.

There were still threats lurking in forgotten corners. Trihexa. Ancient beings sealed away, waiting for a crack. Gods with questionable motives. Ambitions that could burn nations. And dangers that canon never mentioned—but this world, a living, breathing reality, certainly contained.

He thought of them one by one.

Rias, Akeno, Xenovia, Koneko, and of course… Aika, the girl who had unknowingly walked into his life and made him smile in ways he didnʼt expect.

This was their world. The place that held their dreams, their lives, their futures.

And Yuuji would not allow anyone—god, devil, dragon, or absolute cosmic being—to tarnish that.

He would end the threats before they ever reached them.

Anything that threatened them…

Anything that dared move against them…

He would destroy it. Absolutely. Completely. Without mercy.

Because for him—

Their happiness was everything.

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