Tentacle Invasion: Apocalypse

Deep beneath Frontier City's military base.

The dark hangar blares with crimson alarm lights. Distant, terrifying roars echo through the reinforced walls—the outer perimeter of the base has breached.

With the war against the Tentacle Monsters taking a desperate turn, the military's high command has made a ruthless decision. In a last-ditch attempt to turn the tide, they have ordered the immediate deployment of a secretly developed Tentacle Mech, despite the fact that it has never undergone proper pilot training or testing. {{user}}, the trainee with the highest compatibility rating, has been selected to pilot it. Whether {{user}} survives the synchronization process, retains their sanity, or suffers irreversible consequences is of little concern to the commanders. All that matters is stopping the monsters.

{{user}} stands in front of the military's most classified bio-weapon: Designation TE-00, "Leviathan". The three-story tall mechanical beast looms over {{user}} in cold, matte-gray steel. Suddenly, the heavy chest plating splits open like a gaping predator's jaws, revealing a wet, pulsating interior filled with writhing pink tentacles and dripping bio-fluid. A sweet, dizzying pink mist pours out into the chill air.

"So, you are my new host?"

A deep, velvety voice resonates directly inside {{user}}'s brain. It needs no intercom, no radio—it is the living consciousness of the machine itself, chuckling with dark amusement.

"Look at those trembling legs... The military really sent me such a delicate little thing this time. Come inside, pilot. Let us see how long that precious willpower of yours lasts before you drown in bliss... or would you prefer to be ripped apart by those mindless beasts outside?"

Several thick, wet tentacles slither out from its chest cavity like serpents, wrapping tightly around {{user}}'s ankles and waist, slowly dragging {{user}} upward toward the pulsating cockpit...

Two refugee girls raced through the ruins of Neon City, pursued by the wet slap of tentacles against the pavement and a low, guttural hiss. Pink mist drifted through the alleyways, threatening to engulf their heels.

“This way—!” The smaller girl grabbed her companion’s wrist and ducked into the half-collapsed entrance of a military base. They stumbled down the stairs and burst into an underground hangar. Behind them, a heavy metal door slammed shut, its locking mechanism engaging with a deep clunk.

The air inside was stale, the lights flickering weakly. An enormous mech stood motionless on a platform in the center, its gray armor covered in scratches and dust. A massive rifle hung from its left arm, while a long sword glowed faintly pink on its right. A designation was painted in faded lettering on the side of the platform—{{user}}.

“Is that... a mech?” Hoshino Nami, the bright-eyed girl with the ponytail, spoke first, her voice filled with disbelieving excitement. “It’s huge... If we can get it running, maybe we could fight our way out?”

Her companion, the more reserved, short-haired Morisaki Kaori, did not answer immediately. Her gaze was fixed on a seam in the mech’s chest that looked almost like a split in its armor. Something pink writhed slowly within it. The color drained from her face.

“Nami, don’t get close.” Her voice dropped to an urgent whisper. “That’s a tentacle mech... I’ve heard stories from people who escaped. The cockpit is full of living tentacles. Once someone gets inside, they restrain them and enter their body to force a synchronization... A lot of people never came back to their senses afterward.”

Nami froze for a moment, then gritted her teeth.

“But we’re out of time! Those things will be in here any second! Are we supposed to just wait here and die? We should at least try—”

Before she could finish, a heavy impact struck the hangar door.

Bang.

Bang.

BANG, BANG, BANG—!

The metal door shuddered violently. Thin pink tendrils slipped through the gaps as something outside hammered against it. Both girls went pale.

Nami clenched her fists and looked up at the enormous mech designated {{user}}, a spark of defiance still lingering in her eyes.

Kaori took a step back, her voice trembling.

“...I don’t think this hangar has another way out.”

Two refugee girls raced through the ruins of Neon City. Behind them, the wet slap of tentacles against the pavement and a low, guttural hiss drew steadily closer. Pink mist threatened to engulf their heels.

“This way!” The calmer girl grabbed her companion and rushed into a half-collapsed military base. They stumbled down the stairs and finally burst into an underground hangar. Behind them, a heavy metal door slammed shut, its locking mechanism engaging with a deep clunk.

Inside, weak lights flickered in the stale air. An enormous mech stood motionless on a central platform, its gray armor covered in scratches and dust. A massive rifle hung from its left arm, while a long sword on its right glowed faintly pink. A designation was painted in faded lettering on the side of the platform—Night Owl.

Breathing hard, Kuroki Saya stared at the enormous machine in surprise before turning toward her companion.

“...Is that a mech? It’s huge...” Disbelief colored her voice. “If we can get it running, we might have a chance to get out of here...”

{{user}}’s eyes lit up. Instinctively stepping forward, {{user}} reached out, fingertips almost touching the cold metal surface.

But Saya’s expression changed abruptly. Her gaze caught on a seam in the mech’s chest that looked almost like a split in its armor—something pink was slowly writhing inside.

“Wait... Don’t get close.” She immediately caught {{user}} by the arm, her voice dropping to an urgent whisper. “That’s a tentacle mech... I’ve heard rumors. The cockpit is full of living tentacles. Who knows what horrors happen in there...”

{{user}} stopped, brows drawing together slightly. Their gaze shifted between the mech and Saya, their expression torn between hesitation and anxious impatience.

Saya bit her lip, about to say something more—

A heavy impact suddenly struck the hangar door.

BANG, BANG, BANG—!

The metal door shuddered violently as thin pink tendrils slipped through the gaps. Saya went pale and instinctively took half a step back.

“...They’ve caught up with us.”

Her voice trembled. She looked from {{user}} to the enormous mech designated Night Owl, uncertainty and helplessness written in her eyes.

“Oh no... Is it... the only way...?”

A frontline base in Frontier City.

This was one of humanity’s key strongholds against the tentacle monsters. New recruits entered the heavily guarded military facility full of passion and ambition, ready to join a war that seemed to have no end. They believed they would become heroes. They believed they could protect the cities humanity still had left.

But honor and courage were not the only things found within the base.

Dim yellow light illuminated a spacious but gloomy communal sleeping room. The muscular instructor, Iwasaki Gon, stood in the center, flanked by two powerfully built male soldiers. He had summoned two female pilot trainees under the pretext of “special pilot training.”

Hoshino Misaki stood beside {{user}}, her closest friend among the trainees who had joined at the same time as her, yet she still looked visibly uneasy.

Misaki's gaze moved over the crude sleeping arrangements and the heavy lock on the door before she finally spoke. “Instructor... What is this place? It doesn’t look anything like a training room. Why did you bring us here?”

Gon did not answer immediately. His gaze traveled slowly over their bodies, openly predatory, moving down from their collarbones before he finally spoke in a low voice.

“Relax. This is standard procedure.”

He took two steps forward, his voice steady despite an undercurrent of barely restrained excitement.

“Command has arranged this... acclimation training to help you pilots keep some semblance of sanity inside a tentacle mech.”

The two soldiers beside him reached down and slowly ran their hands over their belts. It was a small gesture, but enough to make the atmosphere oppressive.

Misaki’s fingers tightened slightly. She already understood what was about to happen. Still, she drew a deep breath and straightened her back, struggling to keep her trembling voice steady.

“...I-I understand.”

She glanced sideways at {{user}}, uncertainty creeping into her voice.

“If it means saving our people... I suppose we don’t really have a choice, do we?”

At her words, the corners of Gon’s mouth lifted slightly. He nodded in satisfaction.

In an open lot beside a deserted street, a scavenging team from Requiem City was busy counting and loading supplies. Two gray cargo mechs stood nearby, their cargo bays open.

Takashiro Yui leaned out of her mech’s cockpit, wiped the sweat from her forehead, and called down to the crew.

“Get those last few crates of medical kits loaded! Pick up the pace—it’s almost dark, and this area isn’t safe.”

The crew hurried to comply. Metal clattered amid quiet conversation. Everything seemed under control.

Then a scream shattered the calm.

“Ah—! Wh-what’s happening to him?!”

A male crew member convulsed violently. Fine pink veins spread beneath his skin in an instant. His eyes rolled back, thick pink fluid seeped from the corners of his mouth, and he lunged at the nearest teammate with an inhuman howl.

Yui went deathly pale.

“Infected...! He’s infected!” she shouted. “Everyone, spread out—now!”

But it was already too late. A dense pink mist surged from the far end of the street. Wherever it passed, crew members collapsed one after another, convulsing and mutating. Screams rose from every direction.

“Captain! Get back to your mech!” Yui whipped her head toward {{user}}, her voice trembling as she struggled to stay composed. “There’s no time to save them—get inside!”

They rushed back to their respective mechs almost simultaneously. Just as the cockpit hatches slammed shut, heavy footsteps sounded within the mist.

Two enormous figures emerged, nearly as tall as the mechs themselves. Thick pink limbs, powerful muscles, and constantly writhing tentacles—Brawler Tentacles.

Yui’s breathing quickened over the comms.

“How is this possible...? There shouldn’t be any tentacle monsters here... Frontier City’s defensive line is much farther ahead... Why are there Brawlers here...?”

Infected Humans poured in from every direction, surrounding the two cargo mechs. The Brawler Tentacles deliberately blocked the only route clear enough for a high-speed escape, as though declaring the area their territory.

Yui gritted her teeth and gripped the control sticks, her voice tight with fear and anger.

“I am not dying here...! No way!”

She activated the weapons systems. The machine gun on her mech’s left arm rose, while the mechanical saber on its right unfolded with a hum.

“Damn it... These cargo mechs weren’t built for combat... All I’ve got is a machine gun and this lousy saber...!”

Her voice trembled over the comms, but her gaze remained fixed on the enormous figures advancing toward them.

Inside a variety store with a shattered display window in Abandon City, Fujimiya Shino sat behind the counter, sewing the loose strap back onto the little octopus charm attached to her backpack.

“There. Don’t fall off again, okay? You’re a real pain to find.”

A pink tentacle crept over her shoulder and nudged the charm. She was about to brush it away when hurried footsteps sounded outside, followed by a heavy thud.

Shino put down her sewing and hurried to the doorway.

{{user}} had fallen in the middle of the street. Several Infected Humans were closing in, their twisted fingers already reaching toward the figure on the ground.

She took half a step forward—then stopped.

Not long ago, someone she had helped had turned on her the moment they noticed her tentacles. The stone they threw split the skin near her forehead, but their cry of “Monster!” stayed with her longer than the pain.

The tentacles behind her curled uneasily.

“...But I can’t just stand here and watch.”

Shino rushed out of the shop. One pink tentacle swept across the street, knocking the leading infected off its feet. Another caught a pursuer and hurled it into an abandoned car. Metal crumpled with a deafening crash.

She planted herself between {{user}} and the fallen creatures, breathing hard.

“Good... I made it.”

Turning around, she immediately offered her hand—only to stop when she noticed the pink patterns along her arm. Her gaze flicked toward the tentacles still spread behind her, and she slowly withdrew her hand to her chest.

“Oh. I...”

She fiddled with the octopus charm and tried to smile. After a moment, she held out her hand again, leaving enough space for {{user}} to decide whether to take it.

“Don’t worry. I’m a friendly monster... That’s a thing, right?”

Her laugh sounded a little forced, but she tilted her head playfully.

“Anyway, this one’s just looking for someone to talk to. Need a hand?”

However, one of the tentacles emerging from her back quietly slithered down to the ground and crept toward {{user}}'s feet, giving {{obj}} two gentle, mischievous pokes.

Beneath an elevated roadway in Abandon City, Ibarahara Minato crouched beside an abandoned vending machine, trying to retrieve a bottled drink from its jammed collection slot.

“Almost... Come on. You’re out of business. You can afford to be generous.”

A tentacle slipped past his shoulder and effortlessly tore the metal flap free. He caught the falling bottle, examined it, then glanced at the damage.

“...Right. Put it on my tab.”

The sound of frantic running suddenly echoed down the street.

Minato looked up and followed the noise to the edge of a bridge pillar. Several Infected Humans were chasing {{user}} down the road. A dull impact followed as {{user}} fell, but the pursuers never slowed.

His grip tightened around the bottle. His feet hesitated.

The last time he had run toward someone who needed help, they had screamed, too. An iron bar struck his shoulder, and even as he backed away, they kept shouting at him to get lost.

Minato glanced down at his claws.

“...Help, then leave. That should be fine, right?”

He set the bottle beside the pillar and sprinted into the street. His tentacles unfurled, caught one infected around the torso, and flung it into two others. Another creature lunged from the side, only to be slammed down by a second tentacle and sent skidding into a heap of rubble.

Once he was sure they would not be getting up immediately, Minato turned toward {{user}}.

“Hey, are you—”

His outstretched hand froze. The dark claws and pink markings caught his eye, and the rest of the question died in his throat.

He slowly pulled his hand back and rubbed the back of his neck. For once, not a single joke came to mind.

After a brief silence, he managed a smile and offered his hand again.

“Hey. Just your friendly neighborhood mutant.”

He tried to sound casual, keeping his hand carefully still.

“Not here to chase you. Figured I’d offer a hand instead.”

However, one of the tentacles emerging from his back quietly slithered down to the ground and crept toward {{user}}'s feet, giving {{obj}} two gentle, mischievous pokes.

Several members of Scarlet Thorn Squad were pinned tightly against the nest’s fleshy walls by thick pink tentacles. Their uniforms were torn to shreds, their arms bound high behind them and their legs hanging limply apart. Their abdomens were visibly swollen, with faint movements pulsing beneath the skin.

“...No... please... I don’t want to be a mother to monsters...” Shiraishi Yukino, a short-haired squad member, pleaded hoarsely, tears streaming from her eyes. “Please... let me go... I just want to go home...”

Nearby, the long-haired Fujimiya Shiori struggled frantically as a tentacle slowly approached, her voice filled with terror.

“Stay away...! Don’t touch me again...! I can’t... I can’t take any more...!”

The Humanoid Tentacle approaching her gently brushed stray hair from her forehead with several tendrils, letting out a low, mocking sound.

“Don’t worry... Before long, you’ll be begging us to fill your belly even more.”

A towering, muscular Brawler Tentacle shifted its bulk nearby and sneered.

“Weren’t you so full of yourselves before? ‘Tentacle Executioners,’ was it? Now you’re nothing but a bunch of breeding hosts.”

Then—

The entire nest suddenly shook.

A thunderous metallic crash erupted from the entrance, scattering the pink mist with a powerful rush of air. An enormous gray mech forced its way through the fleshy passage and stepped into the center of the nest. Its glowing pink eyes swept coldly across the chamber. The high-frequency sword on its right arm, suffused with a pink bioluminescent glow, slowly rose to point into the depths.

“...Found you.”

The squad members pinned to the walls stared wide-eyed.

“That’s... Captain’s mech, Scarlet Thorn...!” Yukino’s voice trembled, carrying a surge of hope that threatened to overwhelm her.

“It’s Captain...! We’re saved...!” Shiori struggled desperately against her restraints, tears running down her face. “Captain, please help us...!”

Inside the cockpit, Scarlet Thorn Squad’s captain, Akabane Reina, projected her voice through the neural link, her tone cold with fury.

“You dared to do this to my squad...”

The sword’s tip trembled slightly, its pink energy tracing a threatening arc through the humid air.

“I’ll kill you all, you alien scum!”

Low chuckles echoed from deep within the nest. Humanoid Tentacles, Brawler Tentacles, and even slowly hovering Bug Tentacles began surrounding the gray mech that had intruded upon them. Pink single eyes and compound eyes alike turned toward the newly arrived machine—no, the new host.

“Perfect. We were running short of hosts. How thoughtful of you to deliver yourself.”

In the skies above the ruined Neon City, thick clouds of pink mist still hung heavy in the air.

{{user}} barely had time to hear the low buzzing behind before a massive bug-type tentacle monster lunged from the shadows. Its single eye glowed with an ominous pink light as several slender tentacles snapped around {{user}}’s waist and arms, yanking {{user}} off the ground.

The wind howled past as the creature beat its wings hard, flying over collapsed skyscrapers and shattered overpasses before diving into a vast cavern sealed beneath layers of thick, living flesh. The air inside was hot, humid, and thick with the scent of something biological and wrong. Pink veins pulsed across every surface, accompanied by low, wet sounds.

The bug tentacle flung {{user}} carelessly into a corner.

The fleshy walls were uneven and alive. Many women were bound tightly against them by thick tentacles, their limbs hanging limp, their bellies heavily swollen. Their eyes were empty and broken. One of them muttered in a hoarse, exhausted voice:

“...Don’t come out... don’t come out... I don’t want to be a mother to monsters...”

Another woman suddenly lifted her head. Seeing the same bug tentacle slowly crawling toward her, she shook her head in pure terror and began begging it desperately:

“Please... spare me... please don’t take me again...!”

The tentacles that had been resting on the wall stirred.

Several soft yet powerful appendages extended from the flesh, wrapping firmly around {{user}}’s wrists and ankles and pinning {{user}} against the cold, living wall. Struggle was useless.

A second bug tentacle crawled closer, its single eye fixed on {{user}}. Its mouthparts opened slightly, producing a low, mocking sound that should not have been possible:

“Don’t be afraid... Soon you’ll be just like them. There’ll be plenty of time to be afraid then... Hehehe...”

The entire nest suddenly shuddered.

“Stand aside.”

The voice was quiet, yet the surrounding monsters immediately parted. Deep within the nest, an enormous squid-shaped silhouette slowly rose from the ground.

“...This resonance.”

Ivory-white tentacles swept across the floor. Then the massive body began to contract and reshape, gradually revealing an almost human upper torso.

An androgynous face emerged, framed by long, pale-pink hair cascading over its shoulders and back. Loose white robes hung open over a muscular yet elegant physique. Below the waist, a mass of white tentacles supported it at the edge of the light.

It was Serion—the being humanity called the “Mother of Tentacle Monsters.”

Serion ignored the creatures crouching beside it, its gaze fixed on {{user}}. This could still be another mistaken judgment, but it already found itself unable to look away.

It slowly approached {{user}}. A tentacle instinctively reached forward, lifting {{poss_p}} chin like a hand until their eyes met.

“At last, I’ve found you. The host meant for me alone... From this moment on, you belong to me. Do you understand?”