The lab lights flickered gently in sync with the hum of advanced cybernetic machinery. In Dr. Kuseno's underground facility, Genos stood shirtless on a maintenance platform as robotic arms whirred around him, affixing freshly upgraded cybernetic joints and polished titanium plates to his frame. A wall-mounted screen played muted news coverage, but the flashing red banner caught both his and the doctor's attention.
BREAKING: Sea Monster Invasion in J-City – A-Class Hero Stinger on Scene
Dr. Kuseno paused, eyes narrowing. "Another monster attack already? The threat levels are accelerating…"
Genos nodded. "My structural enhancements are complete. New thermal regulation systems, upgraded arm cannons, reinforced servos… I'm ready."
The screen displayed chaotic footage—citizens fleeing as enormous, scaly humanoid sea creatures flooded through J-City's coastal entrances. Their designs were twisted: deep-sea horrors with claws, tendrils, barnacled skin, and luminescent eyes. And at their center stood Stinger, A-Class Rank 11, brandishing his crimson bamboo spear as a small army of sea beasts advanced.
He was holding his ground—for now.
J-City – Central District
The pavement cracked under Stinger's boots as he drove his spear through a Sea Folk soldier's chest, twisting and flinging the monster into a street sign. His breathing was steady, eyes burning with determination.
"Come on, you overgrown goldfish! Who's next?!"
Dozens more sea monsters emerged from the rising tide—hunched, amphibious mutants that hissed and gurgled in a language no human could understand.
Stinger spun his spear into a readied stance, face dripping with sweat. "I could really use some backup right about now…"
Z-City – Desert Outskirts
Elsewhere, under the glaring desert sun, Saitama casually munched on a protein bar as Damian blurred around him at high speed—barely visible, his movements kicking up trails of displaced air and miniature shockwaves.
Damian was hitting 23% the speed of light. Getting faster due to Saitama's training.
With a sudden burst, he zigzagged through the air and grazed the top of Saitama's bald head.
Saitama blinked and smirked. "Heh. You're getting a little better."
Both stopped, hovering above the crater-riddled terrain. Damian floated down, catching his breath. "Okay… break time."
He pulled out his phone and glanced at the screen.
[3 New Messages – Hero Association] [6 Missed Calls – Genos] [Unread Message – Genos: "Sea Folk are attacking J-City! Stinger's in trouble. I'm heading there now!"]
Damian's eyes narrowed. He scrolled through the updates as they pinged:
[Threat Level: Demon – Sea Folk Invasion]
[Estimated Threat-Level Upgrade: Pending – Awaiting further info]
"Looks like everything's still falling into place…" he muttered, checking the time.
2:15 PM.
"Sea King should arrive very soon… Then maybe another hour or so until it escalates…"
He tapped his system interface.
[Main Mission Quest: Stop 2 Dragon-Level or Higher Disasters – 50% Complete]
"Hmmm… I need it to go Dragon-level to count. Which means…" Damian sighed, glancing at Genos's message.
"Sorry, man. You may have to take a beating first."
He tapped Genos's name and made the call.
Midair – Skies Above J-City
Genos leapt across rooftops at full speed, rocket boosters on his back flaring with each jump. He answered the call mid-leap, eyes locked on the horizon.
"Damian?"
"Yo! I just saw your messages. Sorry—I've been training non-stop. Master Saitama's got infinite stamina. I mean, I told him I've got solar-powered endurance, but even I start to feel it after a few hours. Him? He just keeps going like it's nothing. The guy's an absolute freak of nature."
Genos gave a tight chuckle. "Understood. I'm en route now. J-City is getting overrun. A-Class Hero Stinger is already engaged. I'll arrive in approximately 45 minutes."
Damian nodded, idly drawing a circle in the sand with his telekinesis. "Alright, sounds good. Ping me your location and call if you need backup. Also, Genos—watch your blind spots when you engage the enemy."
"Copy that. Sending my live location now. I'll call if things get out of hand."
"Understood."
The call ended. Damian stared at his phone, expression neutral.
"No Saitama this time," he muttered. "This save belongs to me."
J-City – 2:35 PM
A-Class Hero Stinger stood atop a collapsed parking garage, his spear slick with blood and seawater. Around him, the broken bodies of Sea Folk soldiers twitched and dissolved. He was breathing hard, but smiling.
"That's what I call a clean sweep," he said with a confident grin, spinning his bamboo spear with practiced ease. "Who's next?"
Just as he turned to face the street, a shadow loomed behind him.
CRUNCH!
A massive hand engulfed his entire torso—bones snapped, blood sprayed. His eyes widened in shock as he was lifted effortlessly into the air.
The Deep Sea King stood there—hulking, scaled, and grinning with rows of serrated teeth. His bulging muscles rippled under wet, armor-like skin.
"So weak," he said, casually squeezing.
Stinger's body crumpled in his grip like a soda can. With a dismissive toss, the Deep Sea King flung the lifeless hero aside like garbage.
Meanwhile, a few rooftops away…
Lightning Max crouched behind a concrete ledge, peering through binoculars at the chaos below. His breath was steady, but sweat dripped from his brow.
"So that's the sea monster that took out Stinger..." he muttered, narrowing his eyes as he zoomed in on the towering creature.
Lowering the binoculars, Max glanced around. "Looks like he's the last one. Do I move in now… or wait for backup?"
A heavy gust of wind brushed past him.
Huh?
Suddenly, an overwhelming presence flooded the rooftop. Lightning Max's instincts flared—his heart skipped.
Then—he felt it.
The presence of death behind him.
His muscles tensed. Slowly, he turned his head—
The Deep Sea King stood mere feet away, licking his lips.
"Another one? You look crunchy."
Max's eyes widened in horror. "Shit—"
The screen faded to black.
J-City Central, Time: 2:45 pm...
CRASH!
Glass exploded outward from the fifth floor of a damaged office building as a broken body hurled through the air like a ragdoll. A-Class Hero Lightning Max spiraled in freefall, limbs limp, blood trailing behind him in misty arcs.
But he didn't hit the ground.
A hulking figure, bare-chested and imposing, leapt up and caught him in a single arm. The man landed on his feet with a thunderous boom, the pavement buckling beneath him.
Puri-Puri Prisoner, an S-Class, known for his strength… and flamboyance.
Cradling the unconscious hero like a bride, he sighed. "Oh dear… Another pretty boy down." He gently lowered Max to the ground before rising to his full height—muscles glistening with sweat, veins bulging with anticipation.
Nearby, atop a broken lamp post, Speed-o'-Sound Sonic observed the exchange, arms folded, scarf fluttering in the salty wind. His gaze was razor-sharp, fixated on the building above.
A deafening BOOM echoed from the rooftops.
The Deep Sea King had arrived.
He dropped from the shattered office like a fallen god, landing with the force of a meteor. The shockwave shattered windows and sent cars skidding back on their wheels. Dust and debris swirled around his massive, amphibious frame.
Standing tall and terrible in the crater he'd created, he slowly rose to his full height—nearly three meters of chiseled, oceanic muscle. Sea-green scales shimmered like wet obsidian under the afternoon sun, each movement of his frame flexing unnatural power. His chest bore finned ridges like living armor, and bioluminescent gills glowed faintly along his ribcage. His eyes—yellow and vertical-slit—gleamed with feral cruelty.
[Image Here]
He licked his lips slowly, tongue rough like a shark's. "You look… edible," he growled, voice thick and gurgling, as though the sea itself spoke through him.
Puri-Puri Prisoner flexed, stepping forward.
"So you're the one who hurt these beautiful heroes?" His voice cracked with mock sorrow. Then, with sudden intensity, his gaze hardened. "Unforgivable."
Sonic dropped from his perch and landed gracefully beside him, arms crossed. "Tch. That thing's no joke."
Deep Sea King began walking toward them—slow, deliberate, the kind of stride only a being confident in its absolute dominance could manage. Each footstep cracked stone beneath it.
"You look tasty..." he rumbled, spreading his arms slightly as though inviting the fight.
His very presence was suffocating. The air seemed to grow denser, heavier. Rain began to fall from clouds gathering unnaturally fast overhead—thunder rumbling in the far distance, as if nature itself feared him.
Puri-Puri Prisoner cracked his knuckles. "Oooooh my god, I can practically feel the strength emanating from his body... I won't let you hurt anyone else, monster." "Sonic, hunny, step back, let me handle this."
"I don't care who you are," Sea King replied flatly. "You'll die like the rest."
As the two titans squared off, Sonic narrowed his eyes, gauging the situation. He could feel it in his bones—this was not a battle to rush blindly into.
And the Sea King smiled...Then...
A gross sight no one should ever see...
"Angel Style: Angel Rush!" he shouted, happily butt-naked, flying through the air, fists raining down in a blur.
A barrage of powerful punches crashed into the Deep Sea King's torso, each blow echoing like cannon fire. The monster staggered—just slightly—but then smiled. A smile full of fangs.
Without warning, Sea King lashed out.
"Listen to me... the point of a combo is to finish your target in one fell swoop."
A single counterblow—a wet, bone-snapping uppercut—lifted Puri-Puri Prisoner off his feet and launched him backward into a crumbling wall. He hit the ground in a crater of pulverized concrete.
"Ugh… Damn…" the naked S-Class hero coughed, struggling to rise. "Too… strong…"
The Deep Sea King stalked forward through the mist and light drizzle of rain, saliva pooling at the corner of his mouth.
J-City Time: 2:55 PM
The air was tense. The city was quiet and broken.
Amidst the crumbled walls and ruined buildings, the Deep Sea King stood tall—hulking, scaled, and monstrous, but still in his base form. His body was muscular but leaner than it would be moments later. His sea-green hide shimmered with brine, his long tongue slithering lazily across sharp teeth.
"I expected more," he said with a grunt. "Is there no one strong enough in this city?"
Before he could take another step—
WHOOOSH!
A blur tore through the rain like a bullet.
Speed-o'-Sound Sonic landed directly in front of him, crouched low, arms at his sides, a calm smirk on his face.
"You talk too much," Sonic muttered. "Let's see if you can keep up."
In the blink of an eye, he vanished.
WHAM!
His foot collided with the Sea King's temple.
The creature stumbled sideways, surprised—not hurt, but clearly not expecting the sudden assault.
Sonic reappeared behind him, expression cold.
"Too slow."
He attacked again—blitzing the Deep Sea King from all angles. Spinning kicks, darting palm strikes, pressure point jabs—each delivered with deadly precision.
For the first few seconds, it seemed like Sonic was gaining the upper hand. The Sea King grunted, raising his arms to block, snarling in frustration as Sonic zipped past his defenses.
But then—
Patter.
Rain began to fall.
At first, it was a drizzle… then a downpour.
The Sea King paused, his eyes gleaming. His gills pulsed—his body shuddered.
Sonic noticed it. "What the—?"
Muscle began to swell. His shoulders broadened. His chest thickened. His claws elongated. His scales darkened, and steam began to rise off his skin.
His voice deepened.
"Ahhh… now that's better."
Sonic's eyes widened. "He's… getting bigger and faster???"
The Deep Sea King grinned—a wide, toothy smile filled with predatory joy.
"This rain… It restores me. Strengthens me."
Now, he stood nearly twice as wide, his aura of menace palpable.
[Image here]
Sonic launched forward again, faster than before—Fourfold Burial Speed activated.
He aimed for the Sea King's throat—
CLANG!
His strike bounced off harmlessly.
"What?!" Sonic hissed, eyes narrowing.
He leapt, spun, struck again—from above, below, side to side—but now it was different. His blows had no effect.
The Deep Sea King barely moved.
"You're fast…" the monster growled. "But you're not dangerous."
Suddenly—
WHOOOM!
The Sea King lashed out with a monstrous backhand. Sonic ducked by inches, flipping midair as the shockwave behind the strike destroyed a nearby building.
Sonic landed, sliding across wet concrete.
He was breathing harder now.
"Tch… are my moves not fast and strong enough?" he muttered. "Why can't I hurt this thing?!"
He blurred again, but this time the Sea King anticipated it.
SNAP!
A clawed hand shot out and caught him.
Or so it seemed.
The Sea King clenched his massive fist—CRUNCH—only to realize he was holding nothing but fabric.
Torn garments.. A scarf. No body.
He looked up.
Across a rooftop, a familiar silhouette stood—now completely naked, arms crossed over his chest, rain pouring down his toned frame.
Sonic stared back coldly.
"You're lucky I don't have my gear," he said. "Until next time."
And then—whoosh—he was gone, vanishing into the storm.
The Sea King growled, scanning the rain-soaked streets. "Run, little rabbit...I'll find more tasty prey..."
His eyes drifted to the distant shelter...
J-City – Rooftop Adjacent to the Battle
Genos landed with a blast of heat and force, scanning the area with his upgraded optics.
His sensors picked up a massive energy reading—the Sea King was directly ahead.
But before he could move, a blur passed beside him.
A naked blur.
"Turn around if you plan to fight the Deep Sea King," Sonic's voice echoed. "Don't play hero."
Then, he was gone.
Genos blinked. "...Who was that naked pervert?"
His comms activated automatically as he opened the Hero Association relay.
"Reporting: S-Class Hero Puri-Puri Prisoner has been defeated. The Deep Sea King remains active. Threat Level: Demon. Has been raised to Dragon-Level."
Looking out to the city streets, his energy readings showed one large energy signature and thousands of tiny ones.
"Oh no, the shelter!"
He narrowed his eyes. "Engaging now."
Z-City – Desert
The desert echoed with the sound of impacts.
Damian zipped around Saitama in erratic patterns, both of them laughing, their game of high-speed tag leaving afterimages and sonic booms in their wake.
"GOT YOU!" Damian shouted, grazing Saitama's shoulder at hypersonic speeds.
Saitama smirked. "Not bad. Let's take five."
Both stopped, smoke dissipating in a wide desert field shrouded in craters. Damian pulled out his phone and glanced at the screen.
[Hero Association Alert: J-City – Threat Level: Demon, Now Escalation to Dragon-Level Threat!][Mandatory Evacuation and Shelter Protocols Engaged][Eight Heroes Down. One S-Class Confirmed Defeated. One Remaining S-Class En Route.]
Damian's eyes widened slightly.
"It's happening…"
He opened Genos's location—his live tracker blinked right near Shelter 17.
Damian's heart skipped.
"Genos… he's almost there. Please don't die before I get there…"
Saitama leaned over his shoulder.
"Everything okay?" he asked.
Damian jumped slightly. "Yeah—uh, kind of. There's been an update. J-City's being overrun. Sea Folk invasion. The Association's upgrading the threat level to Dragon. One S-Class already down."
Saitama blinked. "Huh… wonder where Genos is?"
Damian pocketed his phone. "He's there. Almost at the enemy's location."
Saitama nodded. "Alright. Guess training's over."
Damian grinned. "Let's go then."
Saitama stood up and turned as if waiting for Damian to lift him into the sky as usual. But instead—
Tap.
"You're it!" Damian said with a smirk. "Beat you there!"
FWOOOOOSH!
He took off into the sky like a missile, sonic booms in his wake.
"I hope I get there in time before Genos gets seriously hurt like in the show."
Saitama blinked. "Wait—huh? You little…"
He sighed, shoulders slouching down...
"I really didn't feel like running anymore…"
And with that, the One Punch Man began jogging—at a casual Mach 1—toward J-City.
To be continued...
A/N: I hope you are enjoying the story so far. In the next chapter, The Deep Sea King Finale. Also, FYI, I rewrote* Chapter 8: Krypton's Final Hour due to a plot hole, particularly Damian's mother's Death. This should improve the story and Damian's Character development. Please check it out if you want. Just gave more clarity and reason for Lysara (Damian's Kryptonian Mother's Death). Anyways, thank you for reading my story! Cheers!