Teacher Han Doyun's Physics Class (It Hurts)

Back in the days not long after he'd been dropped into the Death Game, Han Doyun — a newbie survivor who did nothing but reek of helpless prey — ran headlong into one enormous problem.

Even when a Chaser caught you, you didn't truly die on the spot. You simply endured a horrific near-death experience, after which your body was sculpted anew out of the darkness... but that process was, truly, an unspeakably gruesome one.

And so, slowly, slowly, his humanity wore away. Through dozens, then hundreds of delayed deaths like that, any survivor would inevitably come apart at the seams. It made no difference whether they had been the ones to treat Han Doyun kindly, or the ones who'd picked fights with him that ended in bare-knuckle brawls.

'The fear of death.' Newbie Han Doyun had simply been a slave to that instinct, nothing more. And so he fled the fear in search of a way to stay alive — relaxing whenever it drifted far away, trembling until his mind went blank white whenever it drew near. True or not, there is an old tale that when a camel meets its predator, it buries its head in the sand and squeezes its eyes shut. That was the kind of hollow, meaningless death Han Doyun had met, over and over again.

'There was a time like that.' What finally let him overcome it was a single realization, on an ordinary day.

"Why can't I ever get away from them?"

Han Doyun had thrown that one question at the void countless times. The newbie who spent every run fleeing the Chasers only to be caught and die horribly asked it once more amid the pain and despair, just like always — and then, immediately, he understood. The answer was almost insultingly simple. Because I struggle to survive.

'Aha!'

From the very beginning he had ruled out the option of fighting back — the option of dealing out pain and despair of his own — and done nothing but run far away and strain never to be spotted. The mindset of a human fleeing someone's malice is exactly that predictable, which is why even the greenest rookie Chaser could corner him in a dead end with ease and sink a blade between the shoulders of such foolish prey.

"Then what am I supposed to do?"

The answer was simple. Act on malice himself. No — hurl himself into a far bigger, far deeper malice, and move on the strength of it. Human malice is bottomless and infinite. So if he grounded his every action in malice, wouldn't he finally seize the upper hand in this infinite numbers game — one with his very existence staked on the table?

As long as he remained a human powered by courage, justice, morality, self-esteem — by the resolve to keep the ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠virtues of a decent human being, to live watching everyone else's face, to ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠dream of a future that waited beyond death — he would never, in the end, survive.

...The human called Han Doyun, thinking along those lines, ran through attempt after attempt, and at last he succeeded in swapping out the engine that drove him. From fear to pleasure — because where pleasure is concerned, humans spare no means and count no costs. From hatred to love — because hatred blinds my eyes to the one I'm watching, while love makes me want to understand them more deeply than anyone.

And so the Survivor-Demon Han Doyun was born.

Han Doyun stopped his cheerful clicking and, all at once, began to speak in a quiet voice.

"The wind is blowing. Right? Why is that? Why does the wind blow? The question 'why?' is where all philosophy begins, and physics is no different. There was a time when I carried questions like that everywhere I went, too. Anyway, here's the part that matters. Butcher — today, if you attend my physics class and pass with flying colors, you can take home the neck you've wanted so badly. Mine."

Han Doyun looked higher than usual, as if he'd taken some kind of drug.

[...Doyun, you look pretty high right now.]

Every time Ghost Widow had seen Han Doyun in that state back in the Death Game, fear had come welling up from the deepest floor of her instincts. It was nothing like the fear she felt before the mighty anomaly who hosted the Death Game, or before higher anomalies stronger than herself.

[...That bastard's a madman, dai.]

That serene, hair-raising expression was enough to make even the Butcher — for whom carving up and devouring human beings was mere routine — feel something vaguely, uncomfortably wrong.

[Well, fine... if your heart's set on dying, I'll grant the wish, dai.]

The Butcher hauled chairs and desks in from outside and crammed every last one of them into the science room's only entrance, sealing the way shut. Han Doyun didn't move.

The Butcher heaved a deep sigh and, as if gripped by some premonition, took a single step toward him. Han Doyun didn't move. One more step, and he would be within range for that cleaver to split Han Doyun's skull open. Han Doyun still didn't move. Instead, he opened his mouth.

"First lesson: what, exactly, is friction?"

[Shut your trap, dai! Just die already!]

Cleaver raised high, the Butcher took his step.

"Friction is ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠the force that resists motion between two surfaces in contact. And one of the key factors deciding how strong that force is? The coefficient of friction those surfaces carry."

— Sliide...!

The giant's center of gravity wobbled grotesquely in midair.

[Whoa... whoa...?!]

Then, with a resounding WHUMP, he went down in the most comical fashion imaginable.

"Take, for example, the specific patches of floor I coated with that floor wax from the storage room. Their coefficient of friction is a great deal lower. There are a few spots like that scattered around this science room."

— Click.

— Swish...!

— Click.

Cheogwi pressed the switch twice, and in the brief moment the science room went dark and lit up again, Han Doyun had somehow already crossed to the far side of the room.

"Work out exactly which parts of the floor are slippery and which aren't, and make your way over here. I'll be starting the second lesson right here."

[This... this childish prank...?!]

— THUD! THUD! THUD!!

Out of patience, the Butcher hauled himself up and came charging at speed.

"The second lesson concerns pressure — P. When the same force is applied, the narrower the contact area A becomes, the more explosively the pressure P spikes. A simple little story. Easy to follow, right?"

But this time, without so much as a patch of wax to blame, the giant suddenly began shrieking and rolling across the floor.

[GRAAAAGH!! My... my feeeet!! What is thiiis, daiii!!]

Scattered across the floor were perfectly ordinary Lego bricks.

"Ah, those? Found them in a classroom locker. So... how was it? Did the pressure come across clearly?"

[Wh... why would I, of all beings, be done in by some brats' toys...!]

But why would a powerful anomaly — hardly human at all — be writhing on the ground over nothing more than a few Lego bricks? The reason lay with Han Doyun.

"Among the active skills I brought back with me from the Death Game is one called 'Malice'-Crafted Obstacles. It activates when I lay out obstacles that, judged by ordinary human standards, couldn't possibly threaten a life. When it does, any Chaser caught by one of those obstacles suffers extreme agony and a set period of incapacitation. Lego works. Thumbtacks work. Even an ankle-height rope tripwire will do the job."

[Grrrraaaagh!!]

"Ooh~ looks like the incapacitation lasts a little longer outside the Death Game, huh? I suppose the show did run balance patches, after all."

— Click.

— Swish...!

— Click.

And this time, Han Doyun reappeared by the curtained windows of the science room.

[Ha... he really commits to the bit, and in the most twisted way possible...]

All Cheogwi had been asked to do was turn the lights off and back on at the end of each 'lesson.' That was it. With the strength the newly empowered Cheogwi now possessed, he couldn't bring the Butcher down, but he could certainly have hurt him — and yet Han Doyun, as if he refused to let anyone so much as touch his prey, had assigned him nothing but the light switch.

"You can get up now, can't you? Then it's time for the third lesson. Let's learn about fluid dynamics. This one picks up right where 'why does the wind blow?' left off..."

Murmuring on through his own lecture, Han Doyun took an absent-minded step forward.

— Sliide.

"...Huh?!"

Perhaps he had grown too absorbed in his own teaching — he stepped ‍‍‌‌⁠​​⁠‌​​‍​​‍​‌​⁠‍‌‍⁠⁠‌⁠‌‍‌‍‌‌‌‍⁠​‌​‌​‌‍‌‌‌⁠‍​​‌‍⁠‌‌⁠⁠squarely onto a patch of the very wax he had laid down himself, and went down hard.

"Wh... whoa—?!"

And, blockhead that he was, he couldn't even get straight back up, flailing for balance across the slick floor like a first-time skater. The Butcher did not miss his chance.

[You idiot! Quit the dogshit antics and just die already, dai!!]

This time, at long last, there were no Lego bricks and no waxed floor in his path. He could sprint at full power and swing that human-sized cleaver with everything he had. Half a second more — no, three-tenths of a second — and the human Han Doyun would have become the late Han Doyun: that yapping mouth shut at last, blood fountaining from a severed artery as he crumpled to the floor, a fresh ornament for the Butcher's home.

[Not one of those so-called 'great' Chasers! Me, the Butcher! I'll be the one to take you!!]

Eyes fixed on Han Doyun's despair, the Butcher had apparently wanted to bellow something, and bellow it he did — but Han Doyun simply carried on with the class.

"Now, the reason the wind blows through this classroom? At bottom, you can explain it with a pressure difference. The wind blows because of the gap in air pressure between the inside of this room and the outside air four stories up."

As if he had never once been flailing, Han Doyun seized the curtain beside him and ripped it aside, riding the recoil to slip free of the blade's arc by the width of a single hair. And behind the stripped curtain the Butcher was charging toward at full power, there was no window. There never had been. The glass had been removed and stowed away long ago — which was precisely why the wind had been blowing through the science room.

So why had the Butcher thought nothing of it? Why had he fallen for a trick that, viewed coldly, was almost obvious — a window gone or removed, and a Han Doyun who might well be luring him there to drop him to his death?

The shame of slipping on the wax? The pain and fury of the Lego? Han Doyun, glittering one step away, practically begging to be split open? The obnoxious music still scrambling his mind even at this very moment? Ghost Widow, clicking the light switch on and off and spectating like she was just another paying customer? Or, if none of those — Han Doyun, who at the very, very last moment had shattered the atmosphere of absolute dominance he'd built over that science room and slipped, flailing, in the most pathetic way imaginable?

Of course, the correct answer was all of the above.

The enormous bulk, unable to beat its own momentum, slid on.

[U... Uwaaaaagh!!]

And Han Doyun shoved — driving the Butcher's center of gravity completely past the edge and out into empty air — and then, in a move that defied all understanding, clambered onto his back and began falling from the fourth floor along with him.

"Last one! The fourth lesson is! Gravitational acceleration!"

— WHOOOOSH.

Cold wind tore savagely past the plummeting Butcher and Han Doyun. Their speed kept climbing. The hard brick pavement rushed up to meet them. If a four-meter giant fell from the fourth floor with a whole Han Doyun riding his back, would he live? Even the Butcher couldn't say for certain. But...

[Y... you lunatic! You think YOU'd survive a fall from here, dai?!]

Han Doyun was going to die. Even in this very moment of plummeting toward a messy death, the madman was clinging to his back, pressing on with some nonsensical, worthless little physics lecture.

"Honestly, this last part isn't really physics at all, but hear me out? This world always wants us to fall! And today, you and I are doing exactly that! They say that those who fall are given wings — but that's not the story I want to tell! The story I want to tell is!!! Cats are still gonna be fiiiine!!"

[Just shut your bullshit mouth, daiiiii!!!]

— KRA-KOOOOM!!

With a colossal impact, the entire abandoned school shuddered as if struck by a minor earthquake. And there, in the middle of the Butcher's corpse — now a sodden pulp of meat — stood Han Doyun, wholly unharmed: the man who had added his own meager weight to serve the Butcher an even richer taste of the fall, Cat's Step — the skill that nullifies death by falling — holding firm beneath his feet.

"...Cats are good at landing, y'know."