The Eminence in Shadow vs One Punch Man

The smile on Saitama's face was a rare and terrifying sight. It wasn't his usual placid, slightly goofy grin. It was a wide, toothy, almost feral expression of pure, unadulterated excitement. The kind of look a starving wolf gives a plump, slow-moving sheep. The few remaining citizens and black-clad operatives who saw it felt a chill far colder than any cryo-grenade. They were not witnessing the righteous fury of a hero; they were witnessing the profound joy of a predator that had finally found worthy prey.

Half a mile away, the Regenerator pulled itself from the wreckage of what used to be a bakery, a cloud of flour and pulverized brick dust billowing around it. Its chest, which had been concave a moment before, was now rapidly inflating, the grotesque sound of knitting muscle and regrowing bone echoing through the ruined street. Its single, massive maw opened in a furious, defiant roar. Its programming was simple: destroy the target. The target was still standing. Therefore, it must continue to destroy.

It began to charge back towards the marketplace, its heavy footfalls shaking the very cobblestones.

"It's coming back!" one of the operatives hissed into his communicator, his voice tight with disbelief. "Subject is fully regenerated and re-engaging!"

In his hidden lookout, Dr. Vistis was practically dancing, his spectacles askew. "Perfection! It works! It actually works! The ultimate synthesis of arcane biology and alchemical resilience! It can take his power and heal! We have created a god to fight a god!" His assistant, Fenris, was quietly hiding under a table, whimpering.

Back in the marketplace, Saitama watched the distant, charging figure grow larger. He began doing light warm-up stretches, a few neck rolls, some arm circles. "Okay, okay," he muttered to himself, a giddy energy buzzing through him. "Gotta do this right. Don't want to end it too quickly this time."

The remaining citizens, realizing that "round two" was about to begin, finally scrambled for safety, leaving the marketplace eerily empty save for Saitama and the regrouping black-clad operatives, who were now watching from the rooftops, their mission to "contain" the monster forgotten, replaced by a morbid, professional curiosity to see what would happen next.

The Regenerator thundered back into the marketplace, its eyes glowing with renewed fury. It didn't hesitate. It immediately swung its massive, bone-club arm in a devastating overhead arc, aiming to turn Saitama into a permanent feature of the cobblestones.

Saitama, instead of punching, simply sidestepped. A single, easy, almost lazy movement.

The massive club smashed into the ground where he had been standing, shattering the stones and sending a shockwave through the earth. Saitama, however, was already moving, weaving around the creature's clumsy, powerful attacks.

"A little slow," he commented, easily ducking under another wild swing. "But you're tough! I'll give you that!"

For the first time in a long, long time, Saitama was actually fighting. He wasn't just ending it. He was dodging, moving, assessing. He threw a few light jabs, not with his fists, but with his open palm, just to test the creature's resilience. Each slap sent the Regenerator staggering back, its rubbery flesh denting and then immediately re-inflating with a wet, squelching sound.

"This is great!" Saitama laughed, a genuine, happy sound that was perhaps more terrifying than any battle cry. He dodged another swing, then delivered a sharp kick to the creature's knee. The joint bent at an impossible angle with a sickening crunch. The Regenerator stumbled, but then the joint bubbled, writhed, and snapped back into place, good as new.

On the rooftop, the leader of the operatives watched, his metallic voice laced with awe. "He's… playing with it. Gauging its capabilities. Testing its limits." He looked at his subordinate. "Are our sensors recording all of this? Every micro-expression? Every energy reading, however faint?"

"Affirmative, Commander," the operative replied, his own voice shaky. "We are gathering unprecedented combat data on both the target and the asset."

Dr. Vistis was in a state of pure scientific ecstasy. "Look at it, Fenris! The cellular response is instantaneous! He applies force, the cells compress and distribute the energy, and the arcane matrix immediately triggers hyper-regeneration! It's the perfect feedback loop! He can't destroy it faster than it can heal!" He cackled madly. "I've done it! I've created an immortal engine of destruction!"

Saitama, however, was starting to get a little tired of the game. Dodging was fun for a bit, but he really wanted to see what would happen if he hit it… a little harder.

"Okay, warm-up's over," he announced. The Regenerator, having healed from a dozen minor impacts, roared and charged again.

This time, Saitama met the charge. He cocked his fist back. "Let's try this again, shall we?"

He threw another "Normal Punch." But this one felt different. There was a fraction more intent behind it. A little more oomph.

The punch connected. The result was louder. More definitive.

BOOM!

The Regenerator's entire torso didn't just dent this time; it exploded. A shower of green, gooey, steaming viscera rained down across the entire marketplace, splattering against shopfronts and overturned carts. Its legs and arms, severed from the destroyed torso, flew in opposite directions, crashing into buildings. The head-analogue, with its massive maw, sailed through the air and landed in a public fountain with a final, wet plop.

Saitama stood there, his fist still extended, covered in a fine layer of monster-goo. "Ah," he said, looking around at the mess. "There we go. Guess I just had to hit it a little harder." He looked at his fist, then wiped it on a nearby abandoned tablecloth. "That was… pretty fun, actually. For a second."

A profound silence fell. The operatives on the rooftops stared at the scattered, steaming body parts. In his hidden lab, Dr. Vistis stared at his monitor, his ecstatic smile frozen on his face, his eyes wide with horror.

"It… it…" he stammered. "It blew up… But… but the regeneration… the cellular cohesion…"

And then, his horror turned to a new, even more profound level of scientific terror.

The scattered pieces began to move.

The legs, lying in a heap fifty feet away, began to twitch. The arms, embedded in a wall, began to writhe. The head in the fountain bubbled. And from every single drop of green goo splattered across the marketplace, new flesh began to bubble and grow. The creature's regenerative ability wasn't just centralized; it was absolute. Every single piece was attempting to regenerate into a new, complete creature. The marketplace was about to be filled with dozens, perhaps hundreds, of smaller, angrier Regenerators.

"Oh my gods," Dr. Vistis whispered, his face draining of all color. "The cascade failure… I never tested for total biomass disintegration… The protocol… it's trying to regrow from every part! I haven't just created an unkillable monster… I've created an infinitely multiplying plague of unkillable monsters!" He backed away from his spyglass, his eyes wild with terror. "Fenris! Shut it down! Shut it all down!"

Saitama, however, just looked at the twitching, bubbling goo with a renewed interest. "Huh. So it's like one of those starfish things? Or worms? You chop 'em up and they just make more of themselves?" He watched as a small, malformed, fist-sized Regenerator with tiny legs and a disproportionately large mouth crawled out of a puddle of goo and hissed at him. "That's actually… really cool."

Then, his expression shifted. The smile returned. The wide, toothy, genuinely excited smile.

"So if I punch it into smaller pieces," he reasoned aloud, "I get even more things to fight?"

A dawning, beautiful, glorious realization washed over him. He had found it. He had finally found it. A monster that got stronger (or at least, more numerous) the more he hit it. An opponent he could actually cut loose on, over and over and over again, without the fight ending immediately. A perfect, self-replicating punching bag.

He looked at the bubbling, regenerating mess spread across the marketplace. He looked at the tiny, hissing monster at his feet. He looked up at the moon.

And for the first time in what felt like a lifetime, Saitama felt a genuine, pure, unadulterated thrill. The joy of a second punch. And a third. And a fourth. And a potentially infinite number more.

"Consecutive… Normal… Punches." he whispered, his voice filled with a happy, dangerous glee.

He began to move, a blur of yellow, his fists a whirlwind, striking every bubbling puddle, every twitching limb. Each punch created a small explosion, which in turn created more, smaller pieces, which immediately began to regenerate. The marketplace filled with the sound of hundreds of tiny sonic booms, and the air began to teem with a swarm of small, furious, and utterly doomed monsters.

On the rooftop, the operative commander just lowered his head into his hands. "Report to the Benefactor," he said, his voice a dead monotone. "The asset is lost. The city sector is… likely lost. The Tempest… I think he's having fun."

The alchemist's gambit had not just failed. It had backfired in the most spectacular, most terrifying, and for one bald hero, most wonderful way imaginable.