The proud eldest son of the Duke's Family, Starnassila Berga, burst through the door of my room, radiating a murderous aura in all directions.
"Starnassila Alzen. Where did you get your information? How the hell did you know about this?"
"...Does that matter?"
Gulp!
I took a swig of the strong liquor and chewed on a small piece of cheese.
The musty aroma unique to fermented cheese filled my sinuses, while the salty savoriness and nutty umami soothed my heated tongue.
"Delicious..."
"Starnassila Alzen. Answer properly. Where and how did you get this information? You haven't gone over to the demon side, have you?"
"Brother worries too much. Would the demons even accept me? I'd be useless to them."
"...That's exactly why I'm suspicious. They have ways to make even commoners strong."
"Hmm, you mean demonic energy infusion? Or demonization? Whatever it is, if you think I couldn't resist the temptation due to my inferiority complex... heh, who knows. If the opportunity arose, I might just take it."
"..."
As I openly mocked him, Berga's face twisted in fury, baring his teeth, but I leisurely sipped my drink.
"Kuh... By the way, Brother. Don't you have anything else to say? Like an apology for not believing your little brother's sincere words."
"Nonsense. Spill everything."
"Sigh... You're no fun at all."
"...You want to die?"
His killing intent grew stronger, so I chuckled and downed my drink.
"Kuhhh... So, you want to know the source of the information?"
"Yes. And tell me everything you know."
"Hmm. I just know it, that's all I can say."
"You think this is a joke? Do you need to see blood to snap out of it?"
"Sheesh, like father, like son. Same old crap."
I shook my head and leaned deeply back into the sofa.
"Brother. Whether I tell you where I got the info isn't that important, right? Stopping the demons' plan now that it's exposed—that's the priority, isn't it?"
Sip, haa~
I puffed out thick clouds of cigarette smoke and grinned slyly, making his face harden even more.
"From now on, the Knight Order alone won't cut it. You'll need to bring in the Mage Corps and the Church for an all-out war to minimize the damage."
Especially since the Family Head, Urtega, was afflicted by a curse and wavering.
"...So how do you know all this?"
"I told you, that's not the point. You're so persistent. Seems like pointless preconceptions are messing with your priorities... Brother. You think the Duke's Family falling is no big deal?"
"Watch your mouth, Alzen. I've been holding back, but your arrogant attitude and sloppy speech are pushing it."
"Pfft. Since when did you care? Anyway, just take the info quietly."
"...When everything's over, you'll have to tell me."
"Kuhuhu. Then I'll have to use the Family Head as my shield. Tell him my scary brother is bullying me."
"Father trusts your information?"
"Nah, he seems half-doubting it still."
Well, that was partly because the Family Head wasn't in his right mind.
Still, how the hell were they going to handle that curse?
They could somehow save the capital of the duchy, Terabaon, but if Urtega succumbed to the curse and lost it, everything would be over.
...Well, it'd work out somehow.
"Anyway. I'll list the locations of the black magic circles and doppelgangers I know, so memorize them all. Too annoying to repeat, so once only."
Gulp!
Sip, fuuha~
Downing the strong liquor and savoring the cigarette made my tongue feel even smoother.
"Oh, before that, maybe I should give an overview of the situation? So, the one threatening our Duke's Family right now is a high-ranking demon named Cambello. He's a powerful necromancer, but also a tricky curse sorcerer and shaman. The magic circles he's set up in the castle and Terabaon include decay, plague, and grudge convergence. By now, the underground must be crawling with undead and ghouls."
"...!!"
His already stiff face hardened further at my words.
"The magic circles are exposed, so he's probably panicking. They weren't supposed to be found. Because his Soul Gears skill, 'Pit of Souls,' had cursed key figures, twisting their perception and awareness."
"...And your info alone overturned that?"
"Yeah. He's probably furious and confused right now. Anyway... he doesn't have many options left. His plan, which should've taken weeks or months, fell apart before it even started. But that's why he'll get desperate."
Gulp!
"The biggest threats are the doppelgangers disguised as territory folk and the altars in the basements of the houses they've taken over. If things get dire, he'll sacrifice at those altars to spread dark magic power or summon other demons."
"...I'm going."
He gripped his sword hilt tightly, looking urgent, and turned to leave.
"Wait, where to? Learn the black magic circles and doppelganger locations first. I'll tell you the undead ambush spots underground too, so memorize and go."
"You even know that?"
"What I know. Ready? Here goes."
Blah blah blah.
I rattled off the info nonstop.
I even threw in Cambello's personality and favorite strategies midway; he rubbed his temples like he had a headache.
"Done?"
"Said everything I could think of. Got it?"
"Yes."
"Impressive. Kuhuhu... Oh, right. Have the Mage Corps activate the 'Mana Frequency Blocker' if possible."
"Mana Frequency Blocker? What's that?"
"Huh? You don't know? Oh."
Then I remembered.
The 'Mana Frequency Blocker' was a magitech device that blocks or isolates specific mana frequencies, developed at the start of the original story.
"Never mind... forget I said it."
"..."
Berga gave me a strange look for a moment, then nodded silently.
"Got it."
With that, as he left the room, I waved leisurely at his back.
"Well, now I can..."
I'd done enough, so time to soak in booze and smokes all day.
Was there an easier job than this?
I chuckled self-mockingly and downed another drink.
◇◇◇◆◇◇◇
While I was leisurely enjoying my booze and smokes, someone kicked the door open violently.
"Hey, Alzen. Spill it now. What's a Mana Frequency Blocker?"
"...Even you, Sis? But what's the door ever done to deserve that treatment?"
"Shut up and spill. What's a Mana Frequency Blocker?"
The Duke's Family's second daughter, Starnassila Weller, crossed her arms with a face like even talking to me was repulsive, chin haughtily raised.
"Heard it from Berga? It's a device that blocks specific mana frequencies... but why curious? You couldn't make it now anyway."
"What does that mean? Why not?"
"Tech level issues, materials..."
I froze mid-sentence.
According to the setting document, the Mana Frequency Blocker didn't require advanced tech.
With the right materials, even 50 years ago's tech could've made it.
"Hmm..."
And this was the ducal castle, no less.
They probably had materials in abundance.
But was it okay to do this?
Make something meant to be developed in the original timeline now?
"...Ha."
I pondered seriously for a bit, but it was pointless.
From the start, saving the Duke's Family that was doomed to fall made such details trivial.
"Let me see..."
If I was doing it, better minimize the family's damage.
Gulp!
I downed my drink and recalled the setting document.
...The phrasing came back weirdly detailed and specific.
I'd felt off before... Was my memory always this good?
It felt like the entire setting document was etched in my brain.
"Listen up. Mix fluorite orbs, spirit jewels, mithril, white antelope eyes, and clouded cat brains with alchemy reagents regardless of ratio, then temper with mana. That's the Mana Frequency Blocker. But during tempering, use various mana frequencies. That way, it blocks everything except the input frequency. That part's tricky. Mana frequencies aren't constant, as you know."
"..."
She stared at me suspiciously after deep thought.
"You sure?"
"Sure enough to go experiment. But can you finish before this crisis ends?"
Provoked, she scoffed dismissively.
"Hah, you with no talent wouldn't know what a genius can do. Watch. Half a day."
"Yeah, good luck."
She glared disapprovingly and stormed out.
"So hectic..."
Gulp!
I downed my drink and closed my eyes.
Soon after, faint combat sounds drifted from outside, but I was already fast asleep.
◇◇◇◆◇◇◇
I knew all too well that knowing something intellectually differed from experiencing it firsthand.
I'd learned that lesson to the point of nausea.
"Kugh...!"
But this was over the top.
Starnassila Berga readjusted his grip on his sword, raised his aura, took a steadying breath, and warily eyed the undead circling him.
"Grraaah..."
"Grk, grrrk..."
These were aberrant existences.
Normal undead evoked images of mindless hordes overwhelming with numbers, clumsy and slow, individually weak.
But these were different.
Like intentionally designed for specific roles, they had grotesque bodies that moved fluidly and flexibly, joints and muscles oiled.
And there were so many.
"...Damn it. Worst case."
But that alone wouldn't have made Berga curse.
"Kreeek, kreeeak...!"
"...This'll be tough."
Locking eyes with the red gaze of a ghoul—an upper-tier undead—Berga steeled himself inwardly.
"What're the Mage Corps doing?"
His adjutant, Quino, pressed a finger to his ear and whispered.
"Recovering mana and resting."
"...Hoo."
Frustration surged, but he understood.
They'd just unleashed massive firepower, shredding hundreds of undead and ghouls in one go.
Yet so many remained... Honestly, despairing.
"The Church?"
"...Setting up barriers everywhere for safe zones, treating wounded soldiers."
"I see... Just in case, tell them to prepare for combat."
"Yes, sir."
Berga readjusted his sword, facing the approaching ghouls and undead.
The mysterious info from the Duke's Family's third son, the wastrel Alzen, lingered in his mind.
So, uncharacteristically, he felt like complaining.
According to that info, this crisis wouldn't end with mere undead and ghouls.
The one consolation: They'd destroyed most of the hidden altars and black magic circles.