My Monster Evolution in One Punch Man

Rover shook his enormous head with glee, his tail swishing even faster, clearly showing his delight. The price, however, was that the corridor walls on both sides cracked apart, leaving gaping holes as chunks of rubble crashed down like a violent stone storm.

Now that he had Rover's unmistakable response, the pressure coiled in Hansen's chest finally eased. A wave of fatigue from surviving such a perilous ordeal surged through his already exhausted frame, nearly sending him tumbling to the ground. He was alive. Incredibly, he was still breathing!

Hell yeah!

Even better, he'd just been promoted to serve as the personal chef for a Dragon-level cadre.

"Got it! I'll make sure the next meal knocks it out of the park!"

Radiation Fish: ???

One-Ear: ???

As Hansen's eyes gleamed with a sinister crimson glow and locked onto them, the final two Wolf-level creatures, a fish and a rat, were instantly gripped by fear. Cold sweat poured from their bodies like waterfalls, and they shook like reeds caught in a gale.

"Stay away from us!!!" ×2

…

[Wolf-level monster "Radiation Fish" eliminated. Origin Point +1!]

[Wolf-level monster "One-Ear" eliminated. Origin Point +1!]

Maybe it was his first time enjoying hot food in buffet form, but Rover's tail wagged with unrestrained joy. After feasting to his heart's content, the monster lowered his head, brought his massive snout close to Hansen, and gave him a sniff, then unexpectedly licked him with his warm, squishy tongue.

That single lick nearly made Hansen's heart stop. Luckily, Rover wasn't craving dessert. It was simply his way of leaving his scent behind, a declaration that Hansen now belonged to him.

"Arf! Arf, arwooo~~" (I'm going to bed! Tomorrow, prepare more of those delicious bites~)

Wiping the thick, gooey drool from his face, Hansen managed a helpless grin. "Alright! No problem!!"

Boom! Boom! Boom!

The massive footsteps gradually grew distant, and Rover's mountain-sized figure slowly vanished into the shadows at the far end of the corridor.

"Phew! Man, I am cooked!"

At last, Hansen let out a deep breath. His nerves, which had been stretched tight the whole time, finally relaxed. He had made it out unharmed. And even more than that, he'd turned the situation around.

If he hadn't drawn the cursed job of delivering food to Overgrown Rover, he never would have gotten close to one of the few Dragon-level monsters ruling the top of the monster hierarchy, much less obtained four absurdly powerful SSR powers in one shot.

He glanced down at his hands, now coated in jagged obsidian armor, and felt the searing energy pumping through his veins like lava. Every slight movement radiated the explosive might of his transformed physique. It felt as though he could crush metal with a single grip.

Tiger-level (Upper)!

In a matter of minutes, his threat level had rocketed from mid-Wolf to upper-Tiger in an instant. The exhilaration from such a dramatic surge of power was addictive.

Sure, in a world where freaks like Saitama walked around, others gained strength in even more ridiculous ways. But Hansen was already beyond thrilled with what he'd achieved.

He had survived. And he'd even been marked by Rover. What had begun as a hellish nightmare had suddenly turned into an ideal situation. Who needed anything else?

Suppressing the wave of joy bubbling in his chest, Hansen took a deep breath to steady himself. "No... now's not the time to lose focus!" he muttered. "There are Dragon-level monsters crawling all over the Monster Association. Even Demon-level ones are treated like fodder. This is just the beginning!"

With his nerves hardening again, he summoned the system interface.

===

Non-Human System

Host: Hansen

Current Species: Monster (Unknown Insect Mutation)

Disaster Level: Tiger (Upper)

Abilities:

Innate Ability: 1

1. "Hardened Carapace (N)" Lv3 – Details hidden

Ability Slots: 5/10

1. "Excessive Growth (SSR)" Lv1

2. "Scorch Bomb (SSR)" Lv1

3. "Behemoth Physique (SSR)" Lv1

4. "Beast Instinct (SSR)" Lv1

5. "Basic Regeneration (N)" Lv1

[Origin Points: 4]

===

Staring at the four radiant golden icons, Hansen could feel his heart pounding harder.

"Excessive Growth" filled him with boundless stamina and ever-surging vitality.

"Scorch Bomb" granted devastating ranged firepower, easily capable of vaporizing foes at his level.

"Behemoth Physique" gave him a body more durable and physically powerful than most Tiger-tier monsters.

And "Beast Instinct" honed his battle awareness and danger perception, while offering bursts of rage-fueled strength.

These four powers meshed together seamlessly. Any one of them on its own could be a game-changer for an average monster, but to obtain all four at once? That bordered on miraculous.

Though all four were still stuck at Level 1 and restrained by the limits of his Tiger-class body, nowhere close to Rover's cataclysmic might, their raw potential was undeniable. The only slight letdown was the N-rank "Basic Regeneration" skill he'd copied from that mutant cockroach. It wasn't entirely worthless, being able to heal was always helpful, but next to the golden SSR icons, its plain white glow was an eyesore and took up a valuable slot.

Fortunately, now that his disaster rank had increased, the system had expanded his maximum ability slots to ten. That helped alleviate the slot shortage, at least for now.

His gaze dropped next to the Origin Points counter. Killing the mutant cockroach (lower-Wolf), Radiation Fish (mid-Wolf), and One-Ear (mid-Wolf) had only earned him a total of 4 points.

"One Wolf-tier equals two Wolf-trash... the source point drop rate is seriously trash," Hansen muttered with a sneer. Still, even crumbs from a mosquito's leg were technically food. It was better than nothing.

Refocusing on the abilities list, he tapped the icon for Boros's core skill, "Excessive Growth," anticipation flickering in his eyes.

[Upgrade "Excessive Growth (SSR)" Lv1 → Lv2 requires 1000 Origin Points]

"..."

His lips twitched. He almost spat out blood. A thousand points?! That meant upgrading just one gold-tier skill would require him to slay a thousand low-level Wolf-class grunts. That grind was absurd.

Then again, it was a top-tier ability, something that only monsters at Dragon-level and above should be able to wield. Realistically, he shouldn't even have access to this kind of power yet.

Given how powerful the skill was, a steep upgrade cost... kind of made sense. So unless he went on a nonstop grind or lucked into a high-value encounter, leveling up any SSR-tier abilities wasn't happening anytime soon.

Letting go of that unrealistic fantasy for the time being, Hansen redirected his attention to his core monster trait.

[Upgrade "Hardened Carapace (N)" Lv3 → Lv4 requires 4 Source Points]

Perfect.

Despite being an N-rank ability, it came directly from his own mutation and was technically his innate power, his trademark move. Enhancing it would provide a solid boost to his overall durability. Even so, Hansen didn't rush to spend points. Instead, his gaze drifted toward the auxiliary skill he'd casually copied earlier, "Basic Regeneration."

[Upgrade "Basic Regeneration (N)" Lv1 → Lv2 requires 1 Source Point]

As expected, even low-tier abilities demanded more points as they leveled up. The stronger the skill, the higher the cost, no exceptions. Now that he had a basic grasp of how the system scaled, Hansen made a quick and practical call.

With SSR-tier abilities like "Excessive Growth" and "Behemoth Physique" backing him up, his HP and defense were already far beyond what his current disaster level suggested. Among Tiger-tier monsters, he was operating in a higher bracket altogether. Compared to the marginal boost in toughness he'd get from "Hardened Carapace," the recovery perks of "Basic Regeneration" were simply more valuable.

"System, level it up."

[1 Source Point consumed. "Basic Regeneration" upgraded! Lv1 → Lv2]

As the mechanical voice faded, a subtle warmth began to spread through Hansen's body. It felt like a calm current flowing steadily through his bones and muscles. He could already sense his regeneration quickening. The residual strain and fatigue left over from using "Scorch Bomb" earlier were dissolving at an accelerated pace.

The improvement wasn't earth-shattering, but it was immediate, and noticeable.

"Not bad," he murmured, a flicker of contentment flashing across his face.

With 3 points still remaining, he glanced again at the system display and confirmed his options. He had enough for one more upgrade.

No reason to hesitate.

[2 Source Points consumed. "Basic Regeneration" upgraded! Lv2 → Lv3]

This time, the warm sensation returned with more intensity, almost like a flood of vitality rushing through every fiber of his being. It felt like his very cells were celebrating.

In simple terms, both his HP recovery and stamina regeneration had received a significant bump.

[Remaining Source Points: 1]

With only one point left, there wasn't much he could do now. He decided to hold onto it for later.

The clear and immediate changes to his body brought him a rare sense of calm. Even if it wasn't dramatic, as long as he kept investing points, he would continue getting stronger. That kind of direct, measurable feedback... was addictive.

He took a moment to stretch and feel out his new balance of strength and recovery. His limbs moved with less stiffness, and a subtle vigor returned to his movements. After adjusting to the new state, he closed the system panel and began to refocus.

First priority: get the hell out of here. The whole corridor still stank of Boros's saliva and scorched flesh.

Time to head back to the area where the last mission had been assigned.

According to the fragments he retained from his predecessor's memories, completing missions came with rewards. And chief among them was the very substance responsible for his transformation into a monster, Monster Cells.

These cells had been extracted from the apex lifeform of the Monster Association: Orochi. After being artificially cultivated through specialized processes, they were turned into grotesquely pulsating lumps of living flesh, massive clots that throbbed like diseased hearts. Consuming one could unleash multiple mutations at once, with unpredictable effects. If the user was fortunate, the result could be an enormous leap in power.

Of course, the danger was just as extreme. Many monsters lost control of their bodies after ingestion, overwhelmed by the chaotic energy within and exploding into chunks of meat on the spot.

But monsters... were no longer human. They were twisted lifeforms who had abandoned reason and humanity entirely. With warped minds and an instinctive craving for violence, death no longer carried weight for them.

Hansen didn't want to die. But his thirst for power was just as intense as any other monster's. The decision came without hesitation that he needed those Monster Cells. No matter what.

With the system at his side, he might be able to avoid the worst-case scenario and convert their unstable energy into controlled strength. More than that, he realized it was time to start scouting the environment around him. Being blind in a place like the Monster Association was a quick way to die.

In the manga, most of what was shown about the Association centered around the upper echelons. The rank-and-file structure, inner operations, and number of members had been left vague and undefined. If he wanted to survive, much less thrive, he had to start filling in those blanks.

More importantly, he needed to determine the current timeline.

The Monster Association arc involved multiple turning points, and at the heart of many of them stood a single man, someone dangerously obsessed with heroes.

Garou.

If Garou had already begun making a name for himself, or worse, started slipping down the path to monstrosity, then this seemingly impenetrable underground stronghold might soon become the next siege target of the Hero Association.

And if that happened, two especially troublesome individuals might soon show up, one bald, the other flat-chested and green-haired.

Those two freaks could wipe out the entire arc just by stepping in.

Saitama & Tatsumaki: "Achoo!!" ×2

"Damn it! Who's talking behind our backs?!" ×2

===

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