Chapter 1-5 - Preview of DxD: My Fiancée is Sona Sitri

This is also one of the fanfics that could succeed [DxD: Transfer Student].

So, either this one or [In DxD with Sign-In System!] will become official—share your thoughts in the comments!

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Chapter 1: The Fiancée

.....

"Article One: During the period of cohabitation, neither party shall enter the other's room without permission and must maintain an appropriate distance."

"Article Two: During the period of cohabitation, neither party shall disclose the contents of this agreement."

"..."

"Article Six: During the period of cohabitation, neither shall..."

"..."

"Article Thirteen: The male party must proactively dissolve the engagement upon graduation."

...

Ryou Shiranui looked over the agreement, filled with numerous clauses. He never imagined something like this would happen to him.

A lifelong bachelor in his previous life, he'd somehow gained a fiancée after being reborn into this world.

Even though this fiancée was currently desperate to dissolve their engagement, she was still his fiancée.

"As long as you sign this, I guarantee that the substantial wealth promised to you will be delivered in full... If you have any additional requests, feel free to voice them, as long as they are within my power."

Sona's delicate eyebrows furrowed slightly as she observed Ryou's silence.

If he didn't agree, there would be no way to break the family engagement. After all, he wasn't a Devil, just an ordinary human. She couldn't use a Rating Game to dissolve the marriage contract.

If it had been any other pure-blooded Devil, they might have already revealed their identity and threatened him into signing. However, both her upbringing and the binding nature of the contract prevented her from resorting to such underhanded tactics.

This compromise was already the best she could do.

Moreover, three years of cohabitation were unavoidable, or else she would suffer the backlash of the contract.

"Sorry, I just got lost in thought for a moment... I agree to the terms."

Ryou looked at Sona. Compared to his memories of her, she seemed much more immature. After all, there were still three years until the start of the main storyline.

She had only just entered Kuoh Academy.

Ryou picked up a pen from the table and readily signed his name on the agreement.

At this point, whether he agreed or not didn't really matter.

"I'll have someone come to pick you up tomorrow and help you pack your things."

Sona picked up the agreement, checked it thoroughly, and breathed a sigh of relief, finding no issues.

"No need to trouble yourself. Just give me the address, and I'll go there myself tomorrow."

"Then... alright. I'll be waiting for you at home tomorrow."

With that, Sona didn't linger any longer at Ryou's place.

....................

After Sona left, Ryou was alone in the living room.

Suddenly, his left hand shimmered with an emerald light, and a deep, imposing voice echoed from within.

"Partner, you've got quite the luck with women. If I'm not mistaken, that young girl was a Devil, and a pure-blooded one at that."

"She's Sona Sitri, the heir to the Sitri family, and the younger sister of the current Maou, Serafall Leviathan," Ryou added with a headache.

"The Maou's sister... that's not exactly good news..."

"Ddraig, aren't Devils supposed to be synonymous with deceit and treachery? Being so faithful to a promise doesn't seem very Devil-like."

"Partner, that's just your prejudice against Devils. The vast majority of Devils, especially pure-blooded ones, value their reputation highly."

Ryou was speechless.

Could it be that all the Devils he had slain before were just the 'scumbags' of Devil society?

"Of course, the bigger reason is that your ancestor signed some sort of contract with the Sitri family, forcing them to uphold their promise, even after all this time since the Great War between the Three Factions."

That made sense. Otherwise, why would the Sitri family let their heir marry a human?

"A human who participated in the Great War... Ddraig, do you have any recollection of that? I remember you were involved in the Great War too, although mostly just causing chaos."

Ryou looked at the [Sacred Gear - Boosted Gear], residing in his left hand.

"The white one and I were so focused on our battle that we didn't notice anything else. Besides, during the Great War, with Satans, God, and the Cadre of the Fallen Angels present, the aura of a single human would have been too insignificant."

Ryou supposed that was true.

The main forces of the Great War were the Devils, Angels, and Fallen Angels. Even if humans, Youkai, and others participated, they were merely footnotes.

Fiancée...

A wry smile tugged at Ryou's lips.

This was the first time he'd ever heard that he had a fiancée.

No...

Before his parents passed away, they often jokingly told him, like a fairytale, that he had a beautiful fiancée who would come looking for him in the future.

A thousand years ago, his ancestor had helped a noble family win a war between Gods and Devils, and signed a contract with them.

When the next daughter of that family was born, she would marry the ancestor's descendant.

Even though he was a child at the time, he was mentally mature.

What a load of crap!

A thousand years had passed, eighteen generations of his ancestors were probably in their graves, and they still hadn't produced a daughter? That noble family might have even become dust in the annals of history.

Even if it was true, it was obviously a ploy to deceive his ancestor.

But when Ryou opened the door and saw Sona, who claimed to be his 'fiancée,' some things suddenly became clear.

Perhaps that noble family really hadn't produced a daughter until now.

The birth rate of pure-blooded Devils was notoriously low.

And thinking back to the 'war between Gods and Devils' that his parents used to tell him about, wasn't that just the Great War?

His ancestor must have been a human on the side of the Devils.

<><><><>

Chapter 2: Dragon-Kind Reincarnation

.....

Ryou's phone buzzed. A notification showed that the enormous sum promised by Sona had been deposited into his account.

With more than a dozen zeros, it was an amount of money a Average person couldn't spend in several lifetimes. If this wealth were made public, he would easily rank among the top three richest people in the world.

But to him, all the money in the human world was nothing but useless paper, a string of numbers on a screen.

"Ddraig... the [Dragon-Kind Reincarnation] begins today..."

Ryou casually tossed his phone aside and spoke with a grave tone.

"Because of that little pure-blood Devil..?"

Ddraig was puzzled.

They had killed their fair share of pure-blood Devils over the years, even a descendant of a current Maou not too long ago.

"That's only part of the reason. After all, the [Dragon-Kind Reincarnation] technique has dubious origins. The Underworld is already suspicious, so the sooner it's done, the fewer worries we'll have later."

Ddraig didn't say anything more. They had stored enough dragon blood, and the [Dragon-Kind Reincarnation] was just a matter of time.

It was good to be cautious...

The second floor had been specially modified by Ryou.

The space had been expanded more than tenfold using spatial magic, resembling a large football field with a ceiling dozens of meters high.

In the center was an enormous and intricate magic circle, showing traces of Eastern sorcery, Norse runes, and Abyssal magic, all combined together.

Floating directly above the magic circle was a basketball-sized sphere of blood, radiating terrifying energy and draconic pressure.

This was the concentrated blood he had collected over the years from defeating various Dragon-kind. To this day, they still gritted their teeth at the mention of the current [Red Dragon Emperor].

Being beaten to the ground and forcibly, humiliatingly drained of their blood was the greatest shame of their lives.

"Ddraig, we can begin."

Ryou lay flat in the center of the magic circle and called out to Ddraig.

"[Dragon-Kind Reincarnation]—activate!"

A crimson gauntlet enveloped Ryou's left hand. On the back of the gauntlet, a verdant green jewel embedded within it shone brilliantly.

This was the true form of one of the thirteen Longinus, the [Boosted Gear], also known as the [Red Dragon Emperor's Gauntlet].

Guided by the [Boosted Gear], the dragon blood floating above Ryou transformed into thousands of fine, hair-like strands and seeped into his body through the pores of his skin.

Pain!

Excruciating pain!!

An agony that felt like his bones were being shattered and his flesh was being carved, cell by cell.

The pain shot straight to the top of his head, making his very soul tremble.

The veins on his forehead bulged, his expression contorted in agony. He clenched his fists so tightly that his fingernails dug deep into his palms, drawing blood.

...

All Ryou could do now was endure the pain and let the dragon blood transform him.

Otherwise, all the suffering he had endured up to this point would be for nothing, a complete waste.

"Partner, you have to hold on..."

Deep within the [Boosted Gear], Ddraig silently prayed for Ryou.

In Ddraig's opinion, Ryou might not be the strongest or the most talented host in the history of the [Boosted Gear].

But when it came to madness and audacity, even all the previous hosts combined couldn't compare to him.

He knew he wasn't like the white one's host, who possessed the bloodline of the original Lucifer, nor was he like the host of the [Longinus: True Longinus], who was a descendant of an ancient hero.

Even though Ryou's ancestor had shone brightly during the Great War, that glory had long since faded.

The innate talent and potential of divine and demonic races had always surpassed that of humans throughout history.

To surpass the divine and demonic races, one had to forge a new path.

And the method Ryou had devised was one of the specialties of High School DxD: the [Reincarnation Technique].

To abandon the human body and be reborn into a superior race.

And if he was going to be reborn, he might as well be reborn into the most powerful race.

In the world of High School DxD, the race that could be crowned "the strongest" was, without a doubt, the Dragon-kind...

The Five Dragon Kings, the Two Heavenly Dragons, the Evil Dragons that wreaked havoc on the three realms...

All of them were existences that commanded awe and fear. Not to mention the Infinite Dragon God, Ophis, who had occupied the top spot in the world since the beginning, and Great Red, the Apocalypse Dragon.

............

Therefore, Ryou audaciously stole the [Reincarnation Technique] right under the nose of the Devil innovator, Ajuka Beelzebub, and spent years developing his own unique [Dragon-Kind Reincarnation].

............

Success was always built on sacrifice. When Ajuka Beelzebub developed the [Evil Pieces] for Devil reincarnation, he had sacrificed countless lives as a prerequisite.

However, the unique nature of the [Dragon-Kind Reincarnation] and the use of dragon blood meant that there could be no other experimental subjects.

Success meant reaching for the heavens in a single bound, completely breaking free from the shackles of a weak human body.

Failure meant falling into the endless abyss.

<><><><>

Chapter 3: The Holy Light Dragon

.....

Night fell, and moonlight bathed the earth.

Ryou's [Dragon-Kind Reincarnation] was still in progress.

Six or seven hours had passed.

The dragon blood that had seeped into his body was continuously, forcibly remodeling his physique, a constant cycle of destruction and regeneration..

His snow-white shirt was stained a dark crimson.

The agonizing pain from the transformation continued to assault Ryou's nerve endings.

A layer of delicate scales slowly emerged on Ryou's skin. Ddraig recognized them instantly as dragon scales... This meant that the first stage of the [Dragon-Kind Reincarnation], also the most dangerous and difficult stage, had been successfully completed.

Ryou's body had successfully resisted the erosion of the dragon blood, or rather, adapted to and absorbed it.

Seeing that Ryou had completed the first stage, Ddraig, who was overseeing the [Dragon-Kind Reincarnation], immediately initiated the second stage.

The magic circle beneath Ryou began to glow with a faint silver light.

The magic circle acted as a catalyst. Under its influence, the dragon blood within Ryou's body suddenly became turbulent and began to expand.

Ryou's body also began to expand irregularly, and a bloody mist gradually enveloped him, forming a large cocoon.

A chilling aura emanated from the surface of the cocoon, as if some terrifying life form was gestating within.

At this point, Ddraig breathed a sigh of relief. The results were as he and Ryou had anticipated. All that remained was to wait for Ryou's rebirth.

Ddraig looked at the cocoon that Ryou had become and couldn't help but feel a sense of anticipation.

This was the first instance in history of a human being reincarnated into a Dragon-kind.

What differences would there be between a human reincarnated into a dragon and a naturally born dragon? Would there be a clear difference in their strengths and weaknesses?

All of this could only be determined after Ryou had completely finished his reincarnation.

...

The moonlight intensified, and the cocoon that Ryou had become continued to expand. The aura on its smooth surface grew increasingly turbulent.

Ddraig knew that Ryou was about to be reborn into this world with a new form.

Crack!

A crisp sound echoed in the empty second-floor room.

Crack after crack appeared on the surface of the cocoon, and a powerful, holy aura erupted forth.

If not for the barrier that Ryou had set up in his room, this holy aura would have been detected by every non-human entity in Kuoh Town.

Even so, a tiny, almost imperceptible trace of the holy aura leaked out, vanishing into the night air in an instant.

"This is quite unexpected... I thought it would be a black dragon..."

Ddraig looked in astonishment at the holy white dragon that had emerged.

White scales, like works of art, covered its entire body. Its slender form stretched over a dozen meters long, and it stood six or seven meters tall. Thick, powerful claws were wreathed in white, holy flames that warped the space around them.

A pair of crystalline horns adorned its head, and a pair of white wings, large enough to cover its massive body, sprouted from its back.

"A Pure-blooded Dragon-kind: The Holy Light Dragon, huh..."

Ryou looked at his own massive, holy form in surprise, feeling the endless flow of holy power within him, as well as the immense strength of his physical body.

He was also quite surprised. He and Ddraig had originally assumed he would be reborn as a black dragon.

After all, black dragon blood made up a significant portion of the blood mixture.

But he hadn't expected to be reborn as a Holy Light Dragon, a dragon species unique to Heaven. He had only collected a single sample of Holy Light Dragon blood.

Holy Light Dragons were truly a "minority" among Dragon-kind, and Heaven wasn't exactly easy to infiltrate.

Holy Light Dragons were natural masters of holy power, with an extremely high affinity for the light element. Their physical bodies were also no weaker than black dragons. They were all-around dragons with no apparent weaknesses, making them one of Ryou's most desired dragon species.

"My base power was at the level of an Ultimate-class. But after being reborn as a Holy Light Dragon, I'm now at the peak of the Ultimate-class, just a step away from the Maou-class. Combined with the [Boosted Gear], my power is several times greater than before. The Maou-class is no longer a threat."

"And if I use the [Boosted Gear's] Balance Breaker or even Juggernaut Drive..."

Ryou adjusted to his Holy Light Dragon body and assessed his overall strength. He was now confident that he could face beings like Serafall Leviathan and the Four Great Seraphs of Heaven...

If he went all out, he might even be able to exchange a few blows with a [Super Devil-Beings], although he would have to run away afterward.

There was still a significant gap in power between him and [Super Devil-Beings].

Ryou then returned to his human form.

Having been reborn as a Holy Light Dragon, the fundamental gap between him, Vali, and others had completely disappeared. In fact, he might even be superior now.

He would need to shift the focus of his training. The Holy Light Dragon was now his foundation, and becoming a Dragon King was his next goal.

He could slow down the development of the [Boosted Gear].

After all, developing the Juggernaut Drive form wasn't something that could be achieved overnight.

<><><><>

Chapter 4: Sona and Rias

.....

In a luxurious villa.

Sona sat alone in her girly room, using projection magic to communicate with a friend far away in the Underworld.

Although it was late at night.

For dark creatures like Devils, this was when their day truly began.

"Sona, have you met your human fiancé? How was it?"

In the magical projection, Rias's dazzling crimson hair, captivating emerald eyes, flawless features, and Graceful figure perfectly embodied the image of a goddess in the hearts of many.

She was quite curious about Sona's human fiancé.

"...I don't dislike him, but I can't say I like him either."

Sona thought for a moment and gave her first impression of Ryou.

"So he agreed to your proposal."

Rias caught the underlying meaning in Sona's words.

"He agreed more readily than I expected... I had prepared many plans beforehand, but it seems they were all unnecessary."

Sona nodded slightly.

In truth, she was still a little surprised by how easily Ryou had agreed.

Rias, in the magical projection, displayed a mixed expression of happiness and envy.

She was happy that Sona could finally break free from the shackles of a family arranged marriage and have complete control over her own marital destiny.

The price was not difficult, just living with an ordinary human for three years. It was practically negligible.

But the chains of fate that bound her were not as easy to break as Sona's.

The House of Phenex.

That was a completely different concept from an ordinary person.

"Rias, the new semester at Kuoh Academy is about to start. When are you coming to the human world?"

"In about a week. Mother is still not very supportive of me training in the human world... But this is my only chance now, and I won't back down."

Sona naturally understood what "chance" Rias was referring to.

Gathering a complete set of Evil Pieces, defeating her fiancé in a Rating Game, and thus dissolving the engagement.

If her fiancé were not an ordinary human, she would probably have to take the same path as Rias.

And Rias's mother, Lady Venelana, was a true hardliner. Even if Rias could come to the human world, it wouldn't be smooth sailing.

...

Speaking of peerage members...

Sona had yet to recruit a single member, unlike Rias, who had already gathered her Queen, Rook, and Knight.

It wasn't that she didn't want to recruit members, but rather that she hadn't found any suitable candidates.

When she was in the Underworld, her family had scouted many potential candidates. Most of them were not bad.

But this "not bad" was relative. They were considered above average among the many pure-blooded Devil noble families in the Underworld.

However, they were far inferior to Rias's three peerage members.

As both a close friend and a rival to Rias, Sona naturally wouldn't settle for less.

Fortunately, she had indeed encountered an excellent Queen candidate since coming to the human world, and she had been trying to persuade her for the past few days.

If she could successfully reincarnate her as a peerage member, she wouldn't be much inferior to Rias's Queen, Himejima Akeno.

....

"Huh!"

Sona's body stiffened, and she quickly looked out the window into the night.

"What's wrong, Sona?!"

Seeing Sona's serious expression, Rias immediately asked through the magical projection.

"I felt a surge of pure holy power, but it disappeared in an instant..."

She wouldn't mistake that feeling of intense, almost poisonous, revulsion.

"Isn't there a church in Kuoh Town? It's not surprising to sense holy power there."

Rias explained.

Kuoh Town was a territory jointly managed by the Gremory and Sitri families. Under their tacit consent, the Church had built a church there.

This was already the maximum extent of their tolerance and concession to the Church.

If Heaven sent a high-ranking Angel to Kuoh Town, it would undoubtedly be a declaration of war.

Sona thought about it and agreed. She didn't dwell on it further.

<><><><>

Chapter 5: Moving In

.....

The early morning sun was bright, its rays slightly dazzling.

Ryou packed a few changes of seasonal clothes and cleared away all traces of magic and the arcane from the second floor.

He made sure that no one would suspect that the place had been altered by mysterious forces.

"It's quite far."

The address Sona had given him was almost in the outskirts of Kuoh Town, a considerable distance from his current location. However, it was quite close to Kuoh Academy.

At least, it was much closer than his own house.

............

"You only brought this much stuff...?"

Sona, who was waiting for Ryou at the entrance of the villa, was slightly surprised.

In her mind, even though boys had fewer belongings than girls, daily necessities and various clothes should still be more than what could fit in one bag.

"I don't have many belongings. As for clothes, we should be getting a few sets of school uniforms when Kuoh Academy starts. Besides, Kuoh Academy has a strict dress code that requires us to wear uniforms, so there's no need to bring too many other clothes."

According to the agreement they signed yesterday, he also had to enroll in Kuoh Academy alongside Sona.

If Ryou remembered correctly, Kuoh Academy wasn't supposed to start accepting male students until next year. It should still be an all-girls school right now.

However, when he thought about it...

The entire town of Kuoh was the territory of the Gremory and Sitri families, and the school board of Kuoh Academy was made up of Devils. It wasn't surprising that they could advance the enrollment schedule a bit.

Under Sona's guidance, they walked through the courtyard garden and entered the four-story villa, which was designed in a Northern European castle style and covered a vast area.

He had to say...

The size of the entire villa was almost comparable to a manor. It had front and back gardens, a swimming pool, and even a race track... it lacked nothing.

The interior of the villa was decorated in a fresh and simple yet elegant style.

It was clearly the work of a master designer.

The first floor was the main hall, used for receiving guests and dining.

The second, third, and fourth floors were all guest rooms, likely intended for Sona's future peerage members.

"This is your room. If there's anything you're not satisfied with, or if you have any requests, you can tell me or the butler directly."

Sona led him to the fourth floor and opened one of the many rooms. The amenities inside were comparable to a presidential suite, complete with a walk-in closet, a toilet, a bathroom... everything one could need.

Ryou sensed a change in the spatial dimensions of the room.

Just like the second floor where he underwent the [Dragon-Kind Reincarnation], this place had also been expanded using mysterious means, either magic or the arcane.

An ordinary person might only notice the spaciousness of the room but wouldn't be able to detect anything unusual.

"Thank you. If I have any requests, I'll let the butler know."

The butler was a kindly old man with silver hair. Naturally, he wasn't an ordinary person but an Ultimate-class Devil, likely sent by the Sitri family to protect Sona, their heir.

There were also more than a dozen maids in the villa, all of whom were Devils of varying power levels, mostly ranging from Low-class to Middle-class.

............

"Partner, there are no hidden surveillance magic circles in this room. It seems your fiancée trusts you quite a bit."

Ddraig's voice echoed in the empty room.

"It's not that she trusts me, but that she trusts an ordinary human. The Sitri family has probably already investigated my 'qualities' and naturally feel at ease."

Ryou sat on the sofa in the room and began to draw several Norse runes.

These runes were auxiliary spells for concealing his aura, detecting approaching individuals, and the like.

By setting up these arrays, he wouldn't have to worry about being exposed.

"When it comes to underhanded tricks, the Norse pantheon's arcane arts are the best."

After drawing the last rune, which gathered light elements, Ryou clasped his hands together and formed two hand seals.

The runes covering the walls shimmered with silver light and then slowly merged into the space, disappearing completely.

This was one of the characteristics of Norse arcane arts - their exceptional concealment.

"Hahaha... If that old geezer Odin knew you were describing his precious arcane arts like this, he'd probably faint from anger."

Ddraig joked.

"Probably... That cheap, lecherous old man doesn't have a generous bone in his body."

Ryou shook his head and smiled.

If Odin was angered to death, he deserved it. When Ryou snuck into the Norse pantheon to steal their arcane arts, that old man had, on more than one occasion, sent legions of Valkyries to hunt him down.

Several times, he had almost fallen into the traps that the old man had set.

Once, even Thor, the Norse God of Thunder, a [Transcendental-Being], was deployed. They were totally playing unfair. If he hadn't been quick on his feet, he might have been done for.

...