The Shut-In Prince’s Splendid Social Debut — Me, a Villainous Imperial, Have Spent the Last Fifteen Years Fighting the “Wicked Thoughts” Eating Away at My Mind. When I Finally Returned to High Society, There Were Way Too Many People I Didn’t Recognize

◇◇◇◇

Late at night, before dawn.

Except for the after-party venue, the Serbul residence was wrapped in darkness. Since a noble’s engagement anniversary party lasted two consecutive days, many nobles were staying overnight in the mansion.

After savoring the lavish meal, they slept on soft futons.

Everyone rested quietly so the nobles could recover their strength and greet the next day refreshed.

Two Imperial Knights stood guard at the dungeon entrance.

“Fuaaa…”

“Oi, we’re on duty.”

The senior knight admonished the yawning junior knight.

“…I know, Senpai. But there’s no way anyone would try something inside Serbul-sama’s residence.”

“That kind of carelessness can be fatal. If you’re that bored, do you want to join His Excellency Serbul’s ‘Festival’?”

“I…! No, no! …I’ll pass. Still, as expected of His Excellency Serbul. His play is intense tonight as well.”

From the distance, the sound of drums—don chiki don chiki—echoed faintly.

Serbul’s shouts and clapping were mixed in with it.

Serbul was famous for being party-crazed, and it was well known that any knights or nobles caught up in his games were forced to participate until morning.

“Then concentrate. If someone attacks Lady Fryure and, in the unlikely event her life is threatened, it becomes His Excellency Serbul’s responsibility.”

“Y-Yes…! I’ll be careful.”

Just as the junior knight straightened his back—

“—In that case, you should have paid closer attention to your surroundings.”

A third voice suddenly echoed.

“…………Kah!”

The junior knight’s temple was struck in a surprise attack, and he collapsed unconscious.

Seeing that, the senior knight immediately assumed a combat stance.

He drew his sword and pointed it at the attacker.

“You…! Who the hell are you!”

A suspicious man stood there, his entire body covered in a black robe.

“Fufufu. We are the ‘Demon Worship Cult.’ We have come to collect the offering in the back. So I would appreciate it if you did not raise your voice too loudly…”

As the man declared that—

A group of black-robed figures appeared behind him.

“Wha…”

“Please rest assured, we will not kill you. After all, we need you to properly convey our existence to your superiors—”

The black-robed men attacked the senior knight.

◇◇◇◇

“—Good grief. To drown themselves in wealth and idle away their time like this… the nobles of this country truly are fools.”

The black-robed man spoke with disdain.

Two unconscious knights lay at his feet.

“Without understanding our noble philosophy, they forbid the manufacture of Spirit Armaments… In the end, they simply obey whatever the Perdraon family says.”

“Even the Unified King cannot ignore their words. After all, the head of that family forged a friendship with him.”

“Truly ridiculous. To think we have fallen so low under such a foolish king. When we are the true nobles…”

“—It must be the doing of those ‘Seven Stars.’ They filled the Unified King’s head with unnecessary ideas. Those traitors who once served the Owens family like dogs, whose only talent is switching sides…”

The men complained bitterly.

They were a group that had been pushed out of the Azellan Empire.

That group had formed the core of the Demon Worship Cult.

“Still, one of the Six Flowers—the White Dragon Priestess—has fallen quite low. To think she would be manipulated by such shallow information and corner Margrave Grayash this far…”

“Kukuku, indeed. Without realizing they are dancing in the palm of our hands, they must be sleeping peacefully right now.”

The men laughed.

“Is Lady Fryure down here?”

“Yeah. No mistake.”

The stairs leading underground appeared before them.

“Then let us proceed—as per the Guidance of the Northern Underworld.”

The leader spoke.

“”—As per the Guidance of the Northern Underworld.””

Holding torches, the men descended the stairs.

Unaware that an unexpected person awaited them ahead.

“—We have been waiting for you. Members of the Demon Worship Cult.”

Standing in the basement was a beautiful blue-haired girl.

She was no longer wearing the blue dress from earlier, but Dragon Knight attire.

At her waist hung a finely crafted sword.

“…………Naphna Selene Perdraon? …Why are you here?”

The black-robed man frowned.

“I knew you would come to attack Fryure tonight. So I prepared an ambush here. —To expose the Demon Worship Cult all at once.”

“…Why? There is no way you could have predicted this through our stratagem…!”

“Did you think I failed to notice? —Viscount Zalnand.”

“Wha…?!”

The man’s face was hidden beneath his hood.

Yet he could not conceal his shock at hearing his name.

“It is unfortunate we meet again like this after greeting each other earlier. Don’t you think so, Baron Chemical, Baronet Moankitty, and Baronet Funkicadoo? Of course, I know the others as well.”

“I-Impossible!” “Kuh…!” “How did you know!”

The black-robed men reacted in panic.

All of them had attended the Engagement Anniversary Party earlier and had gathered around Naphna under the guise of forming a faction.

“Viscount Zalnand, you have been offering me ‘advice’ for some time now, haven’t you? You assumed I would be easy to manipulate and approached me. —All to interfere with my investigation.”

It had been exposed.

The man had known Naphna was actively investigating matters in the imperial capital of Kingshaven and had infiltrated her circle.

All his actions had been sabotage meant to keep her from reaching the Demon Worship Cult.

Until now, he believed none of it had been discovered.

“But you should have been completely trapped in our sabotage operations…! There is no way you could know our true identities…”

“I knew from the beginning. I was only pretending to make you lower your guard. In fact, you never suspected me at all, did you?”

“…Tsk.”

She was exactly right.

They had regarded Naphna as nothing more than an easily manipulated pawn.

“I thoroughly investigated all of you. The scale of the Demon Worship Cult. Its members. …However, I could not determine the true identity of the one you call ‘Great Founder.'”

“…”

Viscount Zalnand fell silent.

“—I hear he is extremely cautious and rarely appears in public.”

“Hmph. There is no way you could know our Great Founder’s identity. Even we have not been informed!”

Zalnand sneered triumphantly.

“That is why I decided to lure him out. Using this Engagement Anniversary Party.”

“Hah?”

“It would take too long to explain everything. But if I say just one thing—this entire situation was orchestrated by Margrave Grayash Hraesvelgr-sama and myself.”

“W-What are you talking about…?”

Zalnand trembled.

The beautiful girl before him seemed like some incomprehensible monster.

“Therefore, from the very beginning—you were merely dancing in the palm of my hand.”

“Tsk!?”

Viscount Zalnand had believed until this moment that Naphna Selene Perdraon was nothing more than a charming noblewoman with a prestigious title.

If everything had truly been her strategy—

“Ku, kuku… It seems we underestimated you. …However, you are naïve, Naphna-dono. To come alone to a place like this—how foolish.”

The men threw a volley of throwing knives.

A surprise attack.

“Fufu. —Did you think I came alone?”

At that moment, two young men appeared before Naphna.

One had black hair and red eyes.

The other had blonde hair and blue eyes.

Both knocked the knives aside effortlessly.

“Wha…?! And you are…!”

Zalnand’s eyes widened when he saw the blonde youth.

It was the unexpected Shut-in Prince—Yoan.

“—Naphna-dono, are we done yet?”

Yoan asked.

“Yes. If possible, please capture them without taking their lives. Yoan-sama. Larsen as well. Serta-san, please support the two alongside me.”

With a gentle smile, Naphna calmly issued instructions.

Zalnand trembled with anger.

“…Do not underestimate us. Do you think the Demon Worship Cult can be stopped by forces like this…!”

In the basement of the Serbul residence—

The fire of battle was ignited.

◇◇◇◇

Before I knew it, I was standing on a battlefield.

Our opponents were the Demon Worship Cult.

“Kuh… For a Shut-in Prince…! How can you possess such strength…! Kah!”

I struck one of the black-robed men on the head and knocked him unconscious.

If I estimated their level around 30, then it matched the mid-stage enemies in ERT.

Meanwhile, my effective level felt closer to 60.

Incidentally, the first time the Demon Worship Cult appeared in the original story was when Yoan was still alive.

It served as a foreshadowing event.

The introduction involved a noble girl being kidnapped at the academy.

While investigating, the truth emerged that humans with strong magical power were being used as sacrifices for Spirit Armaments.

That was when the Demon Worship Cult first appeared.

(What was the Founder’s name again…)

The one Naphna said she didn’t know.

Honestly, he had been such a minor villain that I couldn’t remember. His face was completely unremarkable.

“Serta-san.”

“Yes, Naphna-sama.”

Behind me, Naphna and Serta coordinated their magic.

Both were using water magic.

Serta had explained that matching attributes prevented interference.

“”[Water Ball].””

Several water spheres shot forward.

Their killing power was low, but the number of attacks created openings.

If even one connected—

“Hmph…”

“…Goah!”

I slammed another man with the flat of my sword.

Even so—

(We are completely overwhelming them.)

Honestly, I had not expected this.

In ERT, both the protagonist and Naphna started at level 1.

I had assumed Serta and I would need to protect them.

But that clearly wasn’t the case.

Originally, Naphna had the support-type job Dragon Priestess.

She shouldn’t have been this capable with a sword.

Yet now she moved with natural skill.

Her magic was also comparable to Serta’s.

Which was strange.

Serta came from a lineage that was practically the headquarters of magic.

(…Isn’t Naphna unusually strong?)

She definitely had heroine corrections.

Her true capabilities were still a mystery.

And then there was another person.

A black-haired, red-eyed young man moving with absurd speed.

“Damn! What is this guy?! Too fast! …Gyaaa!”

“You monster! Kafu!”

—Larsen Ragnar.

In truth, he was the protagonist of ERT.

An illegitimate child raised coldly within Naphna’s family, he eventually became her attendant after she awakened as the White Dragon Priestess.

He later played a central role in the turmoil of the Seven Kingdoms.

(There is no way he’s level 1.)

Someone who had trained his entire life could not possibly be that weak.

Only someone like me—who spent fifteen years shut inside—would be that low.

(…So why am I fighting here again?)

I recalled the earlier conversation with Naphna.

Her request had been simple.

She wanted my help capturing the Demon Worship Cult.

Honestly, my face had twitched.

Because it aligned perfectly with my own goals.

Still, I was surprised she involved herself so directly.

“—I cannot allow Yoan-sama to involve himself in such dangerous matters. I oppose it.”

Naturally, Serta had objected.

Incidentally, Serta and Naphna had already met earlier.

When Serta crossed her arms under her chest, I thought I saw Naphna’s eyelid twitch.

Probably my imagination.

Although afterward Serta looked oddly satisfied.

“Please help us. It will be difficult for Larsen and me to capture all of them alone. If Yoan-sama assists, it should certainly be possible.”

You know I’m level 9, right?

I should look like minor cannon fodder.

Still—

“Okay.”

I had intended to help anyway.

“Yoan-sama…?!”

“If it’s a request from my fiancée, I can’t refuse. Besides, if something happens, Serta will save me.”

Serta was level 35.

She probably believed she was stronger than me.

“Onii-sama… I understand. But please do not push yourself.”

“Yeah.”

Naphna watched our sibling exchange with curiosity.

“My, how wonderful! Then I shall explain the operation.”

She explained everything.

How she deliberately kept a suspect close.

How she coordinated with Hraesvelgr.

How Fryure had been used as bait.

(That’s pretty ruthless.)

Returning to the present—

Most of the Demon Worship Cult members were already incapacitated.

Only Viscount Zalnand remained.

“…You dare corner us this far! I will at least kill you! Naphna Selene Perdraon!”

Clad in body-enhancing magic, Zalnand rushed forward.

Larsen stood ready to counter—

But suddenly—

“[Dark Smoke].”

“…Tsk!”

Darkness obscured Larsen’s vision.

Taking advantage, Zalnand lunged toward Naphna.

“I’ll take your life!”

“Tsk…”

Naïve.

Even if surprised, Naphna wouldn’t fall so easily.

Still—

Just in case.

I intercepted his sword with one hand.

“Wha…! For a Shut-in Prince to—Gyobe!”

I punched his jaw.

He collapsed unconscious.

That was the end.

When I glanced at Naphna—

She looked slightly stunned.

“—Was that unnecessary?”

“… No. Thank you for saving me.”

For once, the perfect fiancée looked awkward.

And with that—

The battle beneath the Serbul residence ended.

◇◇◇◇

“W-What is the meaning of this…!”

Some time later, Serbul finally arrived.

He still wore excessive party decorations, making him look completely out of place.

“Military Minister Serbul, we captured members of the Demon Worship Cult attempting to attack Fryure. Once interrogated, Margrave Grayash’s innocence will be proven.”

“E… Hah…? What are you saying?”

Serbul clearly could not process the situation.

“Therefore, Fryure is innocent. Military Minister Serbul, may I suggest releasing her from the dungeon?”

“D-Do not be ridiculous! Releasing a criminal—”

“Are you certain? I will prove the Grayash family’s innocence under the name of the White Dragon Priestess. When that happens… where do you think Lord Hraesvelgr’s spear will point?”

Serbul’s face turned pale.

Shortly afterward—

Fryure was released.

“Naphna…”

Fryure’s expression revealed nothing.

“Fryure… I’m sorry. I did something terrible to you…”

Naphna suddenly burst into tears.

Even if it had been necessary, she had placed her friend in danger.

The guilt finally surfaced.

“It’s alright, Naphna. I knew you had a plan.”

Fryure embraced her.

“Eh…?”