Hello, my fellow readers and welcome to my Sonic the Hedgehog/Sailor Moon fanfiction! Sonic Unleashed was my very first Sonic game as a little kid, and I enjoyed it and it became one of my favorite Sonic games along with Sonic Colors! I got the game on the Playstation 2 when I was 9 years old, and I recently downloaded the Playstation 3 version on the Ps4 and had loads of fun! I also recently started watching Sailor Moon and I'm currently on ep 18, so I don't know too much nor too little about it. I never really watched it as a kid, I just heard a lot about it, so a few days ago I decided to see what the hype was all about, and when I watched it, I understood why so many people love this series so much. Also, this is my very first Sonic/Sailor Moon crossover so go easy on me. Anyways enjoy, and don't forget to review, follow, and favorite if you want more! Disclaimer: I do not own Sonic or Sailor Moon! They're rightfully owned by SEGA and Naoko Takeuchi ©.

Prologue

Deep in outer space, a huge red Flagship was floating through the constellations, it was loaded with thousands of fleets of killer robots contained with weapons and satellites. Inside the ship, the sound of a man laughing maniacally could be heard, his name was Dr. Robotnik, Aka Dr. Eggman, the greatest scientific genius in the world.

"Ohohohohohohohoho!" Dr. Eggman cackled like the madman he is, but his laughter was short-lived as he heard the alarms go off. "Hmmm?!"

Outside the Flagship, you could hear a small explosion. Standing in front of the flames was a blue hedgehog with peach skin and green eyes, wearing white gloves and red sneakers. He was known as Sonic the Hedgehog; also known as the fastest thing alive. Eggman's robot fleet aimed their weapons at the speedy hedgehog, who merely smirked, undeterred.

"FIRE!" The mad scientist commanded. The robots then prepared their canons and began relentlessly firing at the hedgehog, who sprinted forward at high speeds while dodging the blasts with ease; a cocky smirk plastered on his muzzle. Sonic jumps in the air and sends a chain of homing attacks on Eggman's robot army. As he finished destroying them, a huge robot swings a punch at Sonic, only for him to slide under the punch and circles around it at high speeds, creating a blue hurricane that lifted it off its feet and into the air before it fell back down, exploding. Sonic increases his speed tenfold and curls into a tight ball, spinning rapidly and hardening his quills, thus cutting straight through Eggman's robot fleet like a living buzzsaw. Soon, Eggman arrived inside a robot of his own, sending a flurry of machinegun fire at the blue hedgehog. But Sonic effortlessly evaded the bullets, before jumping in the air.

"Why you little…!" Eggman growled under his breath, glaring at the blue speedster who was hurling towards him. Sonic then jumps off of the robot's head and uncurls before running across the wall. He was caught off guard as Eggman began firing homing missiles at him.

"Huh?" Sonic questioned, looking back before he ran across the ceiling, dodging the missiles. Sonic successfully avoided them all and ran through the Flagship's hallway.

"You're not getting away!" Eggman shouted, stretching the robot's arm at breakneck speed, reaching for Sonic.

"Uh-oh!" Sonic gasped, trying to get away, but the hand grabbed him and was pulled into its grasp. Sonic grunted as he struggled to break free, but no avail. Eggman grinned evilly, watching his archenemy struggle in his robot's grip. The hedgehog then closes his eyes, concentrating, thus summoning the 7 Chaos Emeralds, which were in his possession.

"What?!" Eggman gasped. He tried to stop the transformation using the robot's other hand, but a powerful yellow blast destroyed both of the robot's hands. Floating in the air, Sonic was now Super Sonic. He then punches through the robot's chest, destroying it completely. Shortly, Sonic turns around to fly after Eggman.

"Uh-oh! Time to go!" Eggman cried, flying away in his hovercraft, with Sonic hot on his tail. Inside the Flagship, Eggman closed the metal doors to get away from Sonic, but his efforts were futile. The supersonic Hedgehog rams through the doors with ease, whilst destroying the rest of the Flagship along with the rest of Eggman's fleet. As Sonic continued chasing Eggman through space, they arrived at Eggman's research facility and he knocks him out of his hovercraft. Sonic blasts through the floor, hovering in the air as he smirked at the evil scientist.

"S-Sonic!" Eggman stammered fearfully, bowing as Sonic lands in front of him. "I-I'm sorry! R-Really! L-Look, go easy on me! I'll turn over a new leaf, I swear! Just give me a chance!" He pleaded.

Sonic chuckled a bit at this. "Well, this is new. Showing remorse, Eggman?" He inquired, smirking. "If you played nice, I wouldn't have to break all your toys." However, what Sonic doesn't know is that he walked right into Eggman's trap.

"Gotcha!" Eggman smirked, pressing a remote control button that made some strange looking machine rise from the floor, surrounding Sonic.

"Wha-?!" The hedgehog gasped, not expecting this. He tried to get away, but an electric force field sucked him in, trapping him. Sonic grunted as he struggled to break free from these weird light blue rings that tied him up but was failing miserably. Eggman laughed proudly at his accomplishment. Then, laser blasters appeared out of the ceiling, charging up before blasting Sonic with light purple beams.

"AAAAAAAAAAAAAAAAAAAAAGGGGGGH!" Sonic cried in agony, volts of electricity coursing through his body. The blast from the beams reverted Sonic to his normal form, whilst releasing the Chaos Emeralds in the process. As Sonic was being electrocuted, he noticed that the energy was being drained from the Chaos Emeralds, slowly losing their color. Outside of the research facility, a cannon was forming underneath it, charging.

"Ho ho ho ho ho!" Eggman laughed. "Oh, I've waited a long time for this!" He then pushed a red button that was in front of him. "FIRE!"

Shortly, the cannon fired a powerful light purple beam, which was heading straight towards the Mobius, blasting it deep into the core. Mobius' regions began to split apart, causing a powerful earthquake that sent the inhabitants of the planet into a frenzy. Then, foul purple energy started to emerge from the planet's core.

"Whoa...!" Eggman muttered, smirking. The purple energy then started to slowly take on the form of a gargantuan beast. Meanwhile, Sonic collapsed on all fours, grunting and trembling in pain from the electrical shocks. Suddenly, Sonic arched his back and began growling. You can hear his bones popping as the hedgehog began growing larger, with his muzzle becoming longer and his torso becoming broader. His fur grows into a thick, lush, heavy dark blue coat, with traits of white fur appearing on the end of his quills and his chest. His arms also become bigger, longer, and more muscular, with dark blue fur sprouting from them. Sonic's white gloves burst into shreds as his hands grew larger, with white fur growing around his wrists, and his fingernails becoming claws, which scratched against the floor, leaving claw marks. His sneakers were also becoming cleats with a grey spiked metal strap and spiked metal soles.

His skin was changing from peach to pale blue, with his lips turning black, and his ears becoming more curved and thin. Finally, Sonic's teeth became razor-sharp fangs. And once his transformation was complete…

"ARRRROOOOOOOOOOOOOOOOOOOOOOOOOOO~!" Sonic unleashed a long, powerful howl. At that moment, the creature fully emerged from the core of the planet. As the machine was shut off, the Chaos Emeralds clinked lifelessly on the floor, which was now black since all the energy was drained from them. Sonic collapsed onto the floor, panting and grunting, feeling rather exhausted from the electrical shocks. The mad doctor laughed triumphantly.

"Success! A brilliant success!" Eggman cried proudly. "It's just as the Gaia manuscripts foretold! The entity that was sealed within the planet has awakened. Now I just need to harness its power, and Eggmanland will finally become to be! NYAH HA HA HA!" He cackled. Sonic staggered on his feet, grunting slightly.

"You've really…gone and done it this time, Eggman!" Sonic snarled, glaring furiously at the mad doctor, his voice much deeper and raspier than normal.

"Ahh, Sonic. That's a good look for you. Festive!" Eggman sneered, taking notice of Sonic's new form.

"So long, friend!" With one push of a button, the airlock behind Sonic began to open. Gasping in shock, Sonic grabbed onto a small ledge in front of him, trying to keep himself from flying out. Yet the force from outside was so strong that he couldn't hold on for long. He flew outside along with the energy-drained Chaos Emeralds, screaming as he plummeted towards the broken planet. Meanwhile, the creature that was sealed within Mobius' core began to emerge into a purple mist, thus scattering all over the world. However, some of its energy didn't linger on Sonic's planet.

Earth, Tokyo, Hiwaka Shrine, Saturday, 11:16 P.M...

It was a calm, summer night in the city of Tokyo. Inside the Hiwaka shrine near Sendaizaka, a young girl with long, raven black hair was lying down on her bed, sleeping peacefully. Her name was Rei Hino, otherwise known as Sailor Mars, one of the five Sailor Senshi. 7 whole months have passed since they've last seen Sonic and his friends. They were transported to Earth/Tokyo due to a freak accident from battling Dr. Eggman that caused an explosion, thus sending them to their world via Chaos Control. They've aided the Sailor Senshi in battling against the Death Busters, as well as foiling Eggman's schemes to enslave their world and turn them into his robot slaves on numerous occasions and searching for the seven Chaos emeralds. It was one hell of an adventure. Soon enough, they were finally sent back to their home world. Unknown to her, dark purple energy was slithering from underneath Rei's bedroom door, and up to her bed. When it touched Rei, she began to toss and turn, clutching her blanket while murmuring in her sleep. As she did this, several images of a demonic, gargantuan creature began flashing through her mind.

Rei had no clue what the creature was. It was darkness, unlike anything they've ever faced before. She grunted and twisted her face, feeling a sharp pain in her head because of the images she was seeing. The Miko girl shook her head, trying to get rid of these horrific visions, but they wouldn't stop coming. She had visions of Sonic being electrocuted and turning into a strange beast. Then, a cannon shot a powerful light purple beam, which splits the planet into pieces, and Sonic was plummeting towards the planet along with the Chaos Emeralds, which were black for some reason.

A trembling, demonic roar echoed throughout her mind. Finally, Rei awoken, sitting up panting with cold sweat running down her forehead. Looking around at her surroundings, she saw the dark energy slithering on the wall and through the window. She looked at her trembling, clammy hands. What was that creature? What was that evil energy that she saw? What has happened to Sonic's planet? And what's happened to Sonic? Is he alive, or is he dead? Rei may not know what's going one, but one thing's for sure, Sonic was in trouble.

"Sonic..." Rei muttered.

To be continued...

Well, what do you guys think? Review, please! Also, in this story, this isn't where Sonic and the Sailor Senshi first meet, they first meet when Sonic and his friends got transported to Earth/Tokyo by a freak accident during a fight with Dr. Eggman, which I'll be writing a story on that soon. I'll also be writing a Sailor Moon/Sonic Colors crossover, which will be a sequel to this story. Any ideas on how the Sailor Senshi should visit Sonic's world? Let me know in the comments.