Epic of Caterpillar

The Necrotic Plane Ruler had laid off his plan perfectly, utilizing Hel as a connection to Helheim's tremendously big Realm Core, he managed to imbue most of his Soul into it, turning it into his vessel, and by using this core's powers plus his own, he stealthily, and below everyone's noses, created a brand new, physical vessel of his own dominion, which didn't belonged to any other soul than his!

Pretty much, it was like a second body, and it wasn't at all like just possessing someone else. Indeed, he had struggled a lot, but he managed to buy enough time, when Zehe cut his connection with Hel, it was already too late anyways… This entire Realm became his second body.

And the smaller Realms filled with rich Primordial, Divine, and Cosmic Energy would become his first meals! His huge tentacles spread across the Astral Road and pierced the cores of these much smaller realms, the people and living beings inside suffered in agony as they were instantly devoured one after another by gigantic jaws.

CRUNCH! CRUNCH! CRUNCH! CRUNCH!

"GRAHAHAHAHA! DELICIOUS! SO MANY SOULS! SO MUCH ENERGY!"

As his laughter spread across the entire world of Genesis, the World's Will panicked, her presence quickly surging from the very center of the Astral Road, sensing this anomaly, which wasn't within her plans at all!

"What do you think you're doing, Necrotic Plane Ruler?! This wasn't within our deal! You were told to slay Kireina's allies and the Supreme Gods not to do this! Are you betraying me?!" She panicked.

"Betraying you?" Laughed the Necrotic Plane Ruler. "I never intended to become your ally! Did you truly thought I would agree to your stupid terms?! I let things be, but I never agreed to them! YOUR WORLD… EVEN YOU, WILL BE EVENTUALLY DEVOURED!"

His tentacles kept spreading and devouring more Realms. He had already devoured four of the smallest, nearest Realms, but he was already aiming for a slightly bigger one, filled with life!

"STOP! YOU BASTARD!" The World's Will panicked.

Every single Realm in the world of Genesis was a small part of her powers. Like a small piece of herself. The reason the majority had a small fragment of her core was because by spreading the around, life would sprout faster, and more energy would be produced from this life, which would go back to her, helping her recover her strength in a futile attempt at trying to reconstruct this destroyed world.

"At this point, he's even worse than Kireina…" She thought, feeling taken aback.

She had honestly never thought things would escalate to this point, all because of her own hate against Kireina, which went so high that she even dared betray her own world to ally that monster, and she ended letting him do as he pleased…

"GEHAHAHAHA! This Realm too! I will devour it!!!" Laughed the Necrotic Plane Ruler.

"STOP!!!" Flora roared with fury, fully knowing her strength couldn't match him, she still valiantly moved forwards!

Countless Totems glowed across her body. Her Divine Powers converging with thousands of gods inside her Divine Realm, the many lives she helped grow became her might, as her entire humanoid body shapeshifted, turning into a titaness made of Yggdrasil Trees, which all fused with her body!

"[Divine Primordial Yggdrasil Tree Fusion]!"

FLAAAAASH!

Her body grew hundreds of times larger, reaching the size of over one hundred kilometers, yet she couldn't even compare to the sheer size of the second body of the Necrotic Plane Ruler, which was almost as big as Earth itself.

"RAAAAAAHHHH!!!"

Her branches spread across his body, and wrapped around his tentacles trying to stop him, especially the huge tentacle trying to devour the Realm he had captured.

Countless explosions spread across his body, wounds opening, as she absorbed his energy and imbued her life energy into him, trying to stop him!

"YOU DAMN PEST!"

The Necrotic Plane Ruler lost his composure once more as he attacked Flora with an endless barrage of beams coming from his countless eyes.

BOOM! BOOM! BOOM! BOOM! BOOOM!

"UNNGGH…!"

Flora's wooden body was covered on countless holes, but kept endlessly regenerating, as she kept trying to spread her roots and branches while constantly attacking with mighty divine techniques.

"FLORA! We need to attack too!" Aura said. "[Astral Road Manifestation Fusion]! [Cosmic Body Transformation]!"

Aura's small human-like body quickly transformed, fusing with the entire Astral Road as he quickly surrounded the entire body of the Necrotic Plane Ruler.

Countless swords and spears made of stars started piercing his utterly titanic body, but to no avail, the wounds were so small and they regenerated so quickly that it felt pointless!

Rimuru and everyone else joined hands, attacking as much as they could as well, everyone surrounded him, attacking his tentacles and stopping him from grabbing more Realms and ending millions of lives in mere seconds.

Roars, explosions, blood, everyone put everything they had to stop this monster, that seemed so relentless in ruining everything they have ever loved.

"HAAHAHAHA! It is USELESS! Your attacks only TICKLE me! My body has ENDLESS regeneration now!" He laughed. "You've come TOO LATE!"

Countless more tentacles grew out of his body, attacking Flora and Aura, piercing their souls constantly, and hurting them really badly! All the others were also being badly damaged, and even Rimuru was constantly gasping for air, without knowing what else she could do!

"Kireina… Kireina-sama…!" She started crying while her body was slowly being pierced countless times. "Masta…! Please… Come back! MASTA!!!"

The crying scream of Rimuru echoed across worlds, universes, and dimensions. Her voice reached her heart, as a huge crack in the Astral Road above the Realm of Helheim opened wide, as a huge titan made of black metal surged from within, constantly growing larger and larger as it channeled the power of many powerful beings within!

"[Abyssal Cosmic Swarm of Gluttony]!!!"

The titan's body suddenly grew to a titanic size as countless, billions of monsters merged into an endlessly devouring swarm, which then shaped into a claw!

"[Chaotic Claw of Demise]!!!"

CRAAAAAASSSSSSHHH!!!

The slicing and piercing attack slashed across the flesh of the Necrotic Plane Ruler's second body, leaving a huge wound behind! Blood and energy ended collapsing out of such a wound, as the claw absorbed it and began dividing into even more claws!

Everyone was left speechless as the claws flew towards them and rescued them, grabbing them and pulling them away from the fight, they couldn't believe what they were seeing!

"T-That voice…" Brontes muttered.

"I-It can't be…" Nesiphae started crying.

"S-She's here…?!" Zehe cried.

"MASTA!!!" Rimuru smiled with tears flowing from her rainbow eyes.

Everyone saw her! Standing atop the enormous metallic titan, a beautiful fairy with big blue and purple wings appeared, long demonic horns, and beautiful black, purple, and red hair waving by the force created by her tremendous aura.

Her aura of pure chaos which spread like an endless swarm of monstrous jaws, eyes, and tentacles, which quickly surrounded the entire second body of the Necrotic Plane Ruler.

Those sharp red eyes glancing directly at him with a furious expression, but then quickly changing right away the moment she heard the voices of her beloved wives.

"I'm back, everyone." She smiled gently, her eyes shining beautifully like two stars in the middle of the night sky.

"KIREINA!"

"KIREINA?!"

While her family and friends cried her name in happiness, the Necrotic Ruler screamed her name in horror.

Author's Note: Title "Kireina's Back To Genesis!"