A Theory Called the Infinite Mana Bug

It was silent.

Thanks to the noise-canceling magic, every voice from the spectators packed into the colosseum was buried in the air and vanished the moment it left their lips. But looking at their faces, you could hear it all perfectly anyway.

Cheers. Screams. Shouts of agreement. Encouragement.

Every eye in the audience was fixed on the six orange magic circles floating above my head.

"Sixth tier — Spirit Realm Materialization."

Through Slave Exploitation, I arranged six magic circles, each already brimming with the mana needed for circulation. Even a magical illiterate like me could deploy high-tier circles correctly, no knowledge required.

But that was all the skill did for me.

This stage — this was the part mages called activation.

What came next was casting. It's like knowing swordsmanship in your head and holding ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠a blade in your hand: without the muscle, you can't so much as lift your arm. The same principle applies — to go from activation to casting, you need magic's own muscle. Mana.

That mana normally takes a lifetime to forge, but they say when everything else is already prepared and all you have left is the casting itself, a little knack is enough. In sword terms, it felt like holding a legendary blade while a swordmaster instructor stood beside me correcting my form — all I had to do was get the angle right and drop my arm.

And Tia had layered mana reinforcement on top of that, which made things considerably sturdier. Of course, at the sixth tier even that was brutally hard, but I'd stayed up all night practicing with her, so I had no grounds for complaint.

I drew out dozens of auxiliary circles, interlocking them between the main ones, careful not to mistake their direction of rotation. Each piece I locked into place set the whole lattice running like the conveyor belts of a factory machine, smooth and beautiful.

"Hmm."

My hand trembled slightly, and the main circle wavered in response. I could not afford to ruin things here. Tia was elsewhere right now, ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠at her own presentation — I'd talked her out of skipping it to assist my demonstration and sent her off. Missing her own showcase because of me would be putting the cart before the horse.

Sixth tier. One rung below the seventh, the limit of human reach. It was said that anyone who touched that domain carved their name into history as a Hero.

Just because activation was possible didn't mean the casting was easy — far from it, especially for someone like me, so wanting in magical understanding.

Even so, I would pull it off.

Rotate. Accelerate. Chant.

Calmly, I completed every step of the process and reviewed the whole thing for anything I'd missed. At the end of it, I clenched my fist.

KWA-BOOM!

The casting finished. The circles that had been spinning faster and faster spread outward across the entire arena.

―Fwaaaaaah!!

The next instant, the world was washed in color.

The colosseum of dirt and sand and brick — the makeshift lecture hall erected atop it was gone without a trace. Birds sang, waterfalls thundered down. A thin mist hung in the air, but fireflies drifted everywhere within it, bright as noon. Every single entity composing this space was a spirit.

Just now, here, I had summoned the Spirit Realm.

What someone had once called — a paradise beyond the clouds.

A legendary high-tier spell that materialized a space from another dimensional plane into reality.

"Oho, the Spirit Realm! Professor Pidia, you've genuinely startled me this time!"

The Academy Principal dabbed his forehead with a handkerchief and burst into hearty laughter.

"Hahaha! That's Professor Pidia for you! So the day has come when I get to see the Spirit Realm with my own eyes!"

"Ahh, it's been ages..."

Vande was delighted as a child, and even Mulan looked deeply impressed.

The spectators were too busy gawking at their surroundings to spare me a glance, marveling as they touched the spirits crowding around them.

I continued the lecture.

"As you can see, by borrowing mana from the future, even a 1st Tier Magic User like myself can wield sixth-tier magic."

The Principal's smile stiffened slightly. He seemed to have remembered what my lecture topic actually was. He hurried over and whispered in my ear.

"Professor Pidia. Isn't this rather dangerous? You cannot go publishing a technique that lets any fool jump their magic up five tiers. The continent will descend into chaos!"

"Rest assured. Trust me, and watch the lecture to the end."

I understood his worry. If this theory worked for everyone, the fallout would be considerable.

"Er, hmm. I have a question," the Principal said as he returned to his seat.

"Mana borrowed from the future must be repaid eventually, no?"

"As I explained earlier — when the deadline arrives, you simply borrow again from the future."

"Repeat that forever, and won't the end come eventually?"

"Time is infinite."

"That is not the same as saying mana is infinite, is it now?"

"Precisely observed."

"Hooh..."

Time to start poking at Phelia.

"There's no need to raise the efficiency of mana or magic output in the present. That would be an inefficient act, in fact. When the mana of the future is infinite, why would you bother?"

―Hey!! Hey, you fraud!!

Phelia's scream from the waiting room carried all the way out here. Apparently she couldn't bear having her own lecture shot full of holes.

"This theory is formally titled the Multi-Temporal Mana Borrowing Theory. The basic formula, summarized, looks like this. Ah — the whiteboard is too narrow to record the full derivation."

I wrote only a fragment of the formula on the whiteboard — the material Sersi had spent all night organizing. The mages, the Magic State's delegation especially, were squirming in their seats, sick with frustration at being unable to see the rest.

"For details, please refer to my paper, to be published hereafter. And with that, I conclude my lecture."

I snapped my fingers. At the same moment, Spirit Realm Materialization ended and the arena returned to its original form.

The noise-canceling magic dissolved. A colossal roar slammed into my ears.

"Insane! That theory is insane!"

"That Spirit Realm was unreal!"

"Amazing!!"

"He's not a Slave Merchant — he's a Great Sage!"

"Pidia! Pidia!"

I descended the steps and returned to the waiting room.

In the arena, six crystal orbs containing recordings of my lecture and Phelia's rose into the air as preparations for the auction began.

The moment I stepped into the waiting room, Phelia came charging at me in fine fettle.

"Hey! Where do you get off with that...! Spouting lies that sound all plausible! What kind of professor are you supposed to be?!"

She must have been truly aggrieved — tears were welling at the corners of her eyes.

"I told no lies. There isn't a flaw in the theory."

"Mana isn't ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠some scrap of paper you scribbled on! It's a real, physical thing! How are you supposed to borrow it from the future? Opening a spacetime channel would cost more mana than you'd get!"

"Turning theory into reality is the work of practitioners, is it not? Then how do you explain the sixth-tier spell I just cast?"

"I-I don't know, any of it! Are you even a 6th-tier Archmage?"

"I'm a 1st Tier Magic User."

"If that theory of yours is real, then you have no brain at all. Do you know why I've never published a single research result, why I never go to the Magic Tower?"

"Couldn't care less."

"Professor Pidia!"

The Principal entered the waiting room, his tone grave.

"May we proceed with the auction as planned? Your lecture and the theory you presented were excellent. Excessively excellent. It could rewrite the entire landscape of magic."

"If another nation acquires the recording and analyzes my demonstration, mages everywhere would grow too powerful and be weaponized — wars would only accelerate."

"And knowing that, you—!"

Phelia started making a racket, so I raised a hand to cut her off.

"There's no problem. This theory cannot be applied in practice."

"Cannot be applied?"

"Correct."

What I had just lectured on was something I'd once read about on a wiki.

Not the wiki I carried with me now — the original, the one I'd browsed before my transmigration.

And specifically, an entry from the DLC.

In other words, the theory I'd presented still had its principles intact, but since the system had been deleted, it was a technique that was "impossible for no discernible reason."

In this world, "borrowing mana from the future" simply could not be done.

A theory alone would have made too little impact and risked losing the contest, so I wedged a demonstration into the lecture — the most memorable spell I could manage.

"What are you saying, then? That your lecture merely looks plausible on the surface, but the contents are an empty shell, Professor Pidia?"

"Precisely. One can hardly hand the world research that could become a devastating weapon, now can one."

"You... you planned all of this from the start?"

Phelia glared at me with a complicated expression. The Principal, meanwhile, seemed to be worried about something else entirely.

"Wait — doesn't this throw your reputation as a professor into question?!"

"The theory itself is sound. Only its execution is impossible. Nations that buy the recording will need years of analysis just to conclude it has no practical value — and even then, I'm the pioneer of the theory. That's an accomplishment, is it not?"

"Professor Alencia, is that true?"

"Well... more research would be needed to say for certain..."

Phelia swallowed her answer, evidently unwilling to admit I was right.

"Hmm. If the two of you say so, I'll take it that there's no problem. Still — do give me some warning about your lecture content next time. My heart cannot take much more of this."

The Principal let out a sigh of relief.

"Hold on — then how did you cast that sixth-tier spell?"

Phelia fixed me with a suspicious glare. I shrugged.

"Trade secret."

Phelia's mouth fell open in dumbfounded disbelief.

"Haha, from a man who can produce that kind of sword-aura, nothing would surprise me. Shall we head out to watch the auction, then? Thanks to the two of you, the Academy's budget is in for a great windfall."

"...Whatever. Waste of time anyway."

"I'll be attending. I'd like to calculate exactly what we're owed."

"I rather expected as much from you. Let's go."

When we returned to the arena, Phelia's crystal orb was in the thick of bidding.

Identical recordings were auctioned three times over. The first orb had already been won by the Magic State for ten thousand gold.

And now the second was being driven up by yet more bidding from the Magic State.

"They're bidding on the same recording again."

"That's how valuable Professor Alencia's formula is. No one in this hall can grasp it at once, so the recording is a must. The Magic State intends to monopolize the formula."

The second orb, too, went to the Magic State at twelve thousand gold.

The third took a slightly different course — an imperial delegation, sweat pouring down their faces, bid it up to fifteen thousand in a desperate fight.

"They overreached. That's probably their entire budget. If they walk away with nothing, the Emperor will have their hides."

The Magic State huddled in conference, then abandoned its bidding. One of ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠Phelia's recordings, in the end, went to the Empire.

Next came mine.

―The Magic State bids twenty-five thousand! Any further bids?

Hm. An interesting picture was taking shape.

"They mean to monopolize Professor Pidia's orb! So that's why they gave up on Professor Alencia's final recording!"

The Magic State won the first two outright, then entered a bidding war for the last one and drove it all the way to thirty thousand before securing their monopoly.

They were surely planning to use it for the war effort — when they eventually realized it had no practical application, they'd weep tears of blood.

"Six orbs for one hundred seven thousand gold! That's another tower we could build! Professor Pidia's share comes to about thirty thousand, I'd say."

"Thirty-two thousand one hundred."

"Haha, exact to the coin. It shall be paid immediately. My congratulations on your victory."

The auction ended to my satisfaction. The contest with Phelia, likewise, had ended in my win.

Looking out over the stands, I saw the students of Earth House sending up cheers and applause for me. At the very least, I knew they were entirely on my side, which was a comforting thought.

Though I couldn't imagine why they were all clutching coin purses in both hands like that.

"Professor Pidia! Show us the Spirit Realm again!"

Even the Water Hall students — Sion's crowd, the ones who took my dungeon studies lectures — came to congratulate me on my victory. My vision for the dungeon studies course felt confirmed as well, and pride swelled in my chest.

I bowed once more to the audience and made my exit. Halfway down the corridor, Phelia glared at me with sulky displeasure.

"Take it."

Having evidently given up on everything, Phelia rolled up her sleeve and funneled mana into her arm. A thin, intricately etched Magic Circuit revealed itself beneath the skin.

I'd expected more resistance, so this caught me off guard. For something won through grueling training, she seemed remarkably unattached to it.

"This isn't exactly something that transplants easily, you know."

"...I prepared for it."

"Then I'll accept it without ceremony."

No sooner had I finished speaking than Phelia seized my arm with both small hands, crossing them as if completing some ritual.