I was Reincarnated as the Youngest Child of a Villainous Noble Family Who Controls the Kingdom from Behind the Scenes

"Hahahahaha! You think your arrows can pierce me?!"

"Ughhh, this is such a painnnn!"

Erik’s apparent right-hand man, Yeti—the contracted demon of Ios—boasted an ironclad defense thanks to his thick fur. Even Rüschel’s arrows couldn’t penetrate it, getting stuck in the fur before reaching the flesh. On top of that, the blizzard breath he exhaled from his mouth sent the arrows flying back, freezing them solid.

"Agh, come onnn! Lord Alphius! Just finish him already!"

"Why are you ordering me around? This isn’t an opponent you can’t beat if you just think a little. Try harder."

"Ehhh?!"

This was typical of Rüschel—the moment she faced even a slightly tough opponent, she’d start whining. And yet, when the enemy was beneath her, she’d gleefully hurl insults like it was nothing.

"Corrosion Blade, Zeroth Sword."

Meanwhile, the sword Erik had created for himself was a nauseating weapon, its metal corroded and decayed. Though it looked too rusted to be of any use, its lethality was unmistakable.

"Here I go—!"

"Hmph..."

Erik swung at me, and I blocked with my demonic sword. The moment our blades clashed, my sword vibrated as if resisting something.

"I see. If this weren’t a demonic sword, it would’ve corroded into uselessness by now."

"Exactly! The one I’ve contracted with is the Impure King, Gyurem! One of the legendary Ten Pillars, so obscure they’re barely even recorded in history!"

"Quite the fascination you’ve got there. With that kind of power, you could’ve easily conquered the world if you wanted."

"The world? How dull!"

Erik forcefully knocked my sword away. His physical abilities and mana both surpassed mine.

"What I crave is a threat that shatters the dull, stagnant monotony of everyday life! The eternal harvest of impurity, reaping lives without end! The moment pristine, untainted humans are defiled—their purity rotting before their very eyes! What I desire is collapse itself!"

Erik’s Corrosion Blade, Zeroth Sword, writhed as droplets of liquid fell from it. The spreading pool beneath us was a sea of decay. Stone, flesh—anything submerged in it would rot away without exception.

"Listen, Alphius! You—no, the entire Balfont family—need to accept the truth! You’re all already rotten to the core!"

"And what would acknowledging that accomplish?"

"You’ll literally rot away! Those self-proclaimed rulers, playing with the nation like it’s their toy—watching them decay in the most literal sense? Now that’s entertainment!"

"...How is that fun?"

Behind Erik stood a beautiful man cloaked in black. That must be the Impure King, Gyurem. A being who presided over corruption while maintaining his own immaculate beauty. He delighted in rotting everything else while keeping himself pristine.

And Erik? His heart had long since rotted away.

Corrupting the innocent heart of a sheltered noble brat must’ve been especially amusing. Though, given Erik’s inherent disposition, he bore some responsibility too.

"Acid Cloud!"

Erik unleashed a sickly green-black mist. Anything it touched—metal armor included—would corrode instantly. And with its wide area of effect, trying to rush through would leave my body in tatters.

"Black Hole."

I sucked the mist into a black hole, but it kept billowing out endlessly, as if infinite. Worse, it morphed into the shape of a dragon, evading the black hole and lunging at me. I kept dodging, but if it caught me, I wouldn’t escape unscathed. Then, without warning, the dragon burst apart, spreading the mist even further, leaving me with fewer places to retreat.

"Thinking I’ll run out of mana? Wrong! This is Gyurem’s power—my own mana expenditure is negligible! I’m sure you’ve heard of Summoning Magic!"

"Ah, the art of efficiently drawing out a contracted demon’s power. You’ve got talent, I’ll give you that."

Even with the right tools, not just anyone could wield them. Compatibility with a demon mattered, and mastering it to this degree was impressive.

But I couldn’t afford to keep praising him. I summoned a Shadow Servant—right above Erik. The Shadow Servant launched a surprise attack, swinging its sword down in one swift motion.

"Hmph! I can see it!"

Erik effortlessly blocked the Shadow Servant’s strike. But at that very moment, another Shadow Servant—the real me, having swapped places—slashed upward from below.

"Gyaaaaah! Gh—ah, ah, that hurts, damn it!"

"You’re tough, I’ll give you that. A normal person would be dead by now."

Despite landing a solid hit, Erik was still standing. Gyurem’s influence had clearly pushed him beyond human limits.

"Don’t get cocky just because you got close!"

"A sword fight, then? Fine by me."

A single graze from Erik’s Corrosion Blade would be dangerous. And with his superior strength and speed, a direct clash would overwhelm me. So I focused on evasion, waiting for an opening.

"Fuhahahaha! What’s wrong? All you can do is defend!"

"『That well-structured face of yours—I’ll rot it away, make it ugly!』"

"Gyurem?"

"『The sight of beauty crumbling is eternally delightful!』"

The voice was unmistakably Gyurem’s.

Come to think of it, a demon of Gyurem’s caliber wouldn’t lend his power to someone like Erik so easily. This had been the plan all along.

"Ahahahaha! 『That pretty face—』I’ll rot it 『right off!』"

"Take turns speaking. You’re overlapping."

Erik’s expression twisted, his features half-overtaken by Gyurem. I swung my demonic sword once, then gave him a look of utter disdain.

"You really think you alone can stay pristine?"

Shadow Servants swarmed Erik from all sides.

"Numbers mean nothing! Petrofield!"

A sea of decay erupted from Erik, spreading rapidly. My Shadow Servants melted like sludge, their forms collapsing. Then, I felt numbness creeping up from my feet—my boots were already crumbling apart.

"Tch…"

"You let your guard down! Now you can’t move at all!"

Just as Erik said, the Petrofield had me trapped, rotting everything in its path. I tried escaping with Shadow Entry, but my Shadow Servants were already disappearing.

So it could even corrode magic itself.

"Petrofield rots everything—even mana! Do you understand what that means, Alphius?!"

"It means if I get close, even my own magic will evaporate."

"『Precisely!』 You and your shadow puppets will rot away into nothing!"

"I see. Then as long as they’re still here, it’s fine."

Just before the Petrofield reached me, the remaining Shadow Servants exploded, releasing a barrage of Dark Needles. Erik couldn’t block them all—several pierced his body. Unfortunately, his durability prevented them from fully penetrating.

"Gh, how…?!"

"You’re neglecting the Petrofield’s upkeep."

The toxic swamp-like field shrank rapidly. Erik clutched his wounds with one hand while gripping the Corrosion Blade with the other.

"It’s… not over yet. Me, losing here? That’s just… boring…"

A vile, pulsating mana gathered at Erik’s feet, slithering up his body.

"Gyurem—lend me all of your power!"

Erik’s entire body mutated. His features refined into an eerily beautiful face—someone else entirely. Twin Corrosion Blades formed in his hands, and a black mantle draped over his back.

What stood before me was no longer Erik—it was the Impure King, Gyurem, in the flesh.

"This is the pinnacle of Summoning Magic—Summon Next. A realm even my so-called ‘benefactors’ never reached. Right now, I am Gyurem’s equal—no, his superior."

"Impressive. You really do have talent."

"Flattery won’t save you now. Alphius, I truly despise you."

"Yeah… Then I guess I owe you an apology."

I glanced at Rüschel, still locked in battle with Ios. She had the upper hand, but it’d take time to finish things.

I’d have liked to wait for her, but there was no helping it.

"Not sure if this counts as payback, but I’ll show you something too. Rüschel!"

"Yeeees~?"

The moment I called, Rüschel zipped over at blinding speed.

Good girl.

Now then—let’s begin.