The Strongest Demon Lord Reincarnated as a Commoner

News of Leo's "Ambient Mana" theory spread through the first-year student body like wildfire. It became the most hotly debated topic on campus, eclipsing even the tale of the broken orb.

"It's a parlor trick! A fluke!" Marcus von Adler insisted to his cronies in the dining hall, his voice a little too loud. "He's probably got some cheap magical artifact hidden up his sleeve. There's no way a commoner could pioneer a new casting method."

"But Professor Croft couldn't explain it," one of his lackeys countered meekly.

"She was just caught off guard! Wait until the physical combat assessments. We'll see how clever his 'theories' are when he's flat on his back," Marcus sneered, stabbing a piece of roast fowl with unnecessary force.

Across the opulent hall, at a table reserved for high nobility, Elara von Valerius listened to the chatter with a thoughtful frown. She wasn't so quick to dismiss it. The memory of that soft, golden light, born from nothing, bothered her. It was illogical, inefficient by all known standards, yet it had happened. It was a crack in the perfect, ordered world of magic she had been raised to master. The commoner, Leo Vance, was no longer just an eyesore; he was an anomaly. And Elara despised anomalies.

Meanwhile, in the far less glamorous East Barracks mess hall, Leo was trying to enjoy a bowl of stew in peace. It was a futile effort. Several other commoner students kept shooting him curious glances, whispering amongst themselves. He had become an unwitting symbol of defiance, a puzzle they all wanted to solve.

"Is it true?" a voice suddenly asked from beside him.

Leo didn't look up. "Is what true?"

"That you can use magic without a core?" The speaker was a girl with tanned skin, a toned, athletic build, and a shock of short, spiky black hair. Her eyes, a sharp and brilliant amber, held a fiery, competitive spark. She wore the standard uniform, but hers was modified for ease of movement, the sleeves rolled up to reveal muscular forearms.

Leo finally turned his head. This was Kaia Ironhand, a warrior-scholar from the northern tribes. He recognized her from the entrance ceremony; she had practically vibrated with battle-lust.

"I never said that," Leo replied, returning his attention to his stew.

"But that's what everyone is saying!" she pressed, plopping down on the bench opposite him, her presence radiating energy. "They said you used the air's own mana! So, can you teach me?"

"No."

Her face fell. "Why not? Are you saving the secret for yourself?"

"Because there is no secret," Leo said with a hint of exasperation. "And I don't know you."

Kaia grinned, a flash of white teeth against her tan skin. "Fair enough! Then let's fix that. I'm Kaia. I'm here to find the strongest fighter in the academy and challenge them. Since you're the most interesting person so far, you're my first target! Let's have a duel!"

Her declaration was loud enough to silence the nearby tables. Everyone turned to stare.

Leo slowly put his spoon down. He looked at her, his eyes as placid as a still lake. "I refuse."

"What?!" Kaia exclaimed, genuinely shocked. "Why? Are you afraid?"

"I'm tired," Leo said, standing up. "And you're loud."

He left his half-eaten bowl of stew and walked out of the mess hall, leaving a bewildered and slightly insulted warrior girl in his wake. Kaia watched him go, not with anger, but with a burning curiosity. His complete lack of fighting spirit was, in its own way, a greater challenge than any boastful warrior could present.

"I'll get you to fight me, Leo Vance," she muttered to herself with a determined grin. "Just you wait."

The next day's schedule brought the students to the academy's vast training grounds. A dozen sparring circles were carved into the earth, surrounded by weapon racks holding everything from blunted steel swords to training staves.

Overseeing the session was a woman who was a living legend.

Commander Evelyn Blade stood before the assembled first-years, her presence sucking the warmth from the air. She was tall and lean, with a long silver ponytail that contrasted sharply with the dark, practical armor she wore. A thin, faded scar ran down from her left eye to her jawline, a permanent reminder of a battle hard-won. Her expression was like granite, her pale blue eyes holding the cold, distant light of a winter star. She was the kingdom's strongest sword, a hero of the last Demon War, and the Head Combat Instructor of Aethelgard.

"Magic is a powerful tool," she began, her voice low and devoid of emotion, yet it carried to every student. "But it is useless if your opponent's sword is at your throat. Here, you will learn to fight. You will learn to survive. Your lineage, your wealth, your magical aptitude—none of it matters here. The only thing that matters is whether you can stand after your opponent has fallen."

Her cold gaze swept over the students, making even the arrogant Marcus von Adler stand a little straighter.

"We will begin with basic sword forms," she announced. "Pick up a training sword. I will demonstrate the first stance."

Commander Blade picked up a blunted longsword. For a moment, she just held it. Then, she moved. It wasn't fast, but it was perfect. Her body flowed into the 'First Guard' stance with an economy of motion that was breathtaking. Every muscle was aligned, her center of gravity was perfect, her posture was an unbreachable fortress. It was the living embodiment of martial perfection.

The students scrambled to imitate her, picking up swords and awkwardly trying to copy the pose. The results were a mess of poor footwork and unbalanced shoulders.

Leo picked up a sword. It felt alien in his hand—a primitive, crude tool. In his past life, his weapon had been reality itself. Still, the muscle memory of his new, mortal body absorbed the Commander's movements. He fell into the stance.

He didn't try to be perfect. He just relaxed, letting his body settle into the form naturally. It resulted in a stance that looked... lazy. His shoulders were slightly slumped, his grip on the sword looked loose, and his eyes were half-lidded.

Commander Blade began to patrol the lines, her footsteps silent on the packed earth. Her critiques were brutal and concise.

"Valerius. Your wrist is too tense. You sacrifice flexibility for power."

"Adler. You're overcompensating with your lead foot. A child could trip you."

"Brightwood. Hold the sword, don't pray to it." Luna squeaked and nearly dropped the weapon.

Then, the Commander's shadow fell over Leo. She stopped, her cold eyes scanning his pathetic-looking stance from head to toe. The other students held their breath, anticipating a verbal evisceration that would make the others seem like compliments.

Commander Blade was silent for a long, tense moment. Her brow, which seemed permanently etched with a stoic frown, furrowed just a fraction deeper.

Any other instructor would have seen a dozen flaws. Laziness. Inattention. A weak grip. But Evelyn Blade, a true master of the sword, saw something else.

She saw that despite his slumped shoulders, his center of gravity was flawlessly anchored to the earth. She saw that his 'loose' grip would allow for an explosive, unpredictable change in direction. She saw that his 'lazy' eyes were not unfocused, but were taking in the entire field with minimal effort. His stance wasn't the 'First Guard' from the textbook. It was... the conclusion of it. It was a stance one would take after a thousand battles, where every shred of unnecessary tension had been stripped away, leaving only pure, unadulterated efficiency.

It was impossible. A first-day student couldn't possibly possess that level of insight. It was a fluke. A coincidence.

"Your stance is sloppy, Mr. Vance," she said aloud, her voice as cold as ever. "Fix it."

"Yes, ma'am," Leo replied with a distinct lack of enthusiasm, shifting his posture to more closely resemble the textbook form.

Commander Blade moved on, but her mind was elsewhere. She had felt something similar once before. Ten years ago, on a blood-soaked battlefield, facing a high-ranking demon general. The creature had moved with that same impossible, tension-free efficiency. The memory sent a phantom chill down her spine.

She shook her head. The war was over. This was just a lazy commoner. There was no connection.

"Now," she announced, her composure regained. "Find a partner and engage in light, controlled sparring. I want to see you apply the form."

Instantly, a figure appeared in front of Leo, a wide, competitive grin on her face. "Me and you, Vance!" Kaia Ironhand declared, pointing her training sword at his chest. "No refusing this time. It's a class assignment."

Leo sighed. It seemed unavoidable. "Fine. But be careful."

"Oh, I will be," Kaia chuckled, misinterpreting his words as a warning to him. "I'll be careful not to beat you too badly."

She took her stance, a much more aggressive and impressive version of the First Guard than the others. The spar began.

Kaia lunged, her blade a blur. It was a fast, powerful, and well-executed thrust.

Leo didn't block. He didn't dodge. He simply took one small, lazy-looking side-step. Kaia's sword whistled past him, its momentum carrying her slightly off-balance. In that same motion, Leo's hand, the one not holding the sword, came up and gently tapped her on the shoulder.

"You're open here," he said, his voice quiet.

The entire exchange took less than a second. Kaia froze, her attack completely neutralized, her body exposed. She hadn't even seen him move. It was like he had teleported a foot to the left.

She backed away, her grin gone, replaced by stunned disbelief. "How...?"

"You put too much power into your first move," Leo explained calmly. "You were committed before you knew my response."

"Again!" she demanded, her competitive fire now mixed with a dose of real shock.

She attacked again, this time with a flurry of slashes. Leo didn't raise his sword. He just moved. His feet seemed to glide over the ground, weaving a pattern that kept him just outside her blade's reach. He didn't retreat; he just... wasn't there whenever her sword arrived. It was like trying to hit the wind.

After her fifth swing met nothing but air, she was panting, frustrated. Leo, on the other hand, hadn't broken a sweat. He still looked like he was about to fall asleep.

"Stop just dodging and fight me!" she yelled in exasperation.

"Alright," Leo said with another sigh.

He raised his sword. Kaia tensed, preparing for his attack.

Leo didn't attack. He just held his sword out, its tip pointed at her.

And then Commander Blade's voice cut through the air, sharp as a guillotine.

"Ironhand! Stop!"

Kaia froze, startled. She looked at the Commander, who was staring at them, her face pale, her knuckles white where she gripped her own sword.

"What is it, Commander?" Kaia asked, confused.

"Your spar is over," Evelyn said, her voice tight. She was looking at Leo, and for the first time, her icy composure was gone, replaced by a look of stark, utter shock.

Kaia didn't understand. But Elara, watching from a few feet away, did. So did a few other prodigies of combat.

When Leo had raised his sword, he had done nothing. But at that moment, every instinct in their bodies had screamed at them. It was an invisible, suffocating pressure. A sense of absolute, inescapable checkmate. If Kaia had taken one more step, if she had even twitched, she would have been defeated. Not by a strike, but by a concept. His sword wasn't just pointing at her; it was at the logical conclusion of their fight, a point in time and space where her defeat was an absolute certainty.

It was not a sword stance. It was an echo of a fundamental law of combat they had never known existed.

Commander Evelyn Blade stared at the lazy commoner, and the image of the demon general from her nightmares superimposed itself over his frame.

Who in the nine hells, she thought, her heart pounding in her chest, is Leo Vance?