Disclaimer: I don't own Fairy Tail, Rave Master, and Edens Zero, or Kamen Rider and they belong to their respected owners.
Kamen Rider Ghost in Grateful Damashii was fighting off some Gammas, pulled the RevolTrigger summoning two Parka Ghost.
MUSASHI!
EDISON!
RASSHAI!
"Miyamoto Musashi has appeared!" Musashi Parka Ghost announced.
"I'm Edison." The Edison Parka Ghost says.
The Parka Ghost started to assist Ghost in fighting off two Gamma Superiors before finally destroying the Gamma Superiors.
Ghost was fighting off Denki Gamma and Book Gamma before pushing them back. Ghost calls in for the Parka Ghost assistants and gets ready for the finisher.
ZOKU ZOKU IKU ZŌ~! ZOKU ZOKU IKU ZŌ~!
As Ghost created the Eyecons symbol behind him before the electricity course all three of them made the Parka Ghost be absorbed back to the Eyecon Driver G. The faceplate of the Grimm Damashii vanished from the armor plates confusing the Rider.
Denki Gamma and Book Gamma combined their power and shot out colorful energy at Ghost sending the Rider back making him lose the Grimm Eyecon and de-henshin back to Haru Gurori.
Haru heavily pants before realizing what happened, "I see. The Grimms are fighting…"
Invel walks to the Grimm Eyecon and grabs it from the ground.
"I see Animus-sama has overestimated you," Invel says, as Denki Gamma and Book Gamma held Levy and the professor Yuuchi hostage.
"Let me go!" Levy cried out.
"Levy! Professor Yuuchi!" Haru called out in worry.
Haru turns to see "Animus" before "he" turns into Gammaizer Liquid.
"A new Gammaizer!" Haru exclaimed.
The Gammaizer Liquid walks towards Haru before giving the deceased boy an uppercut sending Haru back.
"There's no need to analyze your new power," Invel says before giving Haru a deadly smirk. "This is the end."
"Not yet! I believe…" Haru started to get up. "…in my infinite potential!"
Haru's chest began to glow like a ball of white energy left his ghostly body. He grabbed hold of the ball of light turning it into a new Eyecon. He pressed the button once making the Eyecon let a chorus chime.
Haru stood back up as he inserted the new Eyecon into his Ghost Driver. He then pulls the Detonate Trigger, closing the Glint Eye.
MUGEN SHINKA! EYE!
The Ghost Driver let out a new standby announcement as the Driver released the new Damashii.
BATCHIRIMINĀ...BATCHIRIMINĀ!
"Henshin!" Haru then pushed the trigger as he was given a new Transient form.
CHO KAIGAN! MUGEN!
Angelic rock music started playing as his new white Damashii Parka flew around Haru.
KEEP ON GOING! GO, GO, GO! GO, GO, GO! GO, GO, GO! GOTTA! GHOST!
The new Damashii landed on Haru completing the transformation. They got a good look at Haru's new form as white feathers fell around him.
He wore a greyish-sparkling armor dominantly over his dark grey bodysuit beneath it as the armor covers his chest, sidearms, thighs, and frontal legs with multicolored infinity symbols on them. He had an orange Ghost symbol on the center of his chest. He had black gloves and boots along with black knee pads. He wore a white hooded trench coat with orange outlines, it also had white shoulder pads that had two openings of greyish-sparkles, and a hook & eye that had orange outlines. He had a white helmet and had a clear face shield over his half-white, half-black faceplate with orange eyes. Between his eyes and over the face shield was a multicolored horn with a grey center. Burning life towards infinite evolution! Converting the strength of his heart into power, he became Kamen Rider Ghost Mugen Damashii.
Everybody watched Haru's new form, Levy in awe, Invel excited to see this new power, Gammaizer Liquid waited to see Ghost's new power, and in the Gamma World Animus also waited to see the power of Haru's infinite potential.
Ghost then takes off his hood.
"It's the shining ghost from before…" Levy murmurs.
"So this is your power?!" Invel grinned.
"Observing. Commencing elimination." Gammaizer Liquid says.
"Return the two of them." Ghost says.
Ghost turns into golden dust as he passes through Gammaizer Liquid, he pushes back Invel and knocks the two Gammas away from Levy and the professor.
"What is this?!" Invel questioned as he activated his Eyecon.
"Levy," Ghost looked at his friend.
Levy understood and guided the professor to safety.
Ghost began to fight Invel and the Gammas with ease with dodging and blocking their hits.
"Observe. Analyze." Gammaizer Liquid created a ball of water before throwing it at Ghost trapping him.
Denki Gamma and Book Gamma then combine their powers again before a colorful energy blast at the trapped Rider.
"Did they get him?" Invel ponders as he sees the huge explosion.
As the smoke dies down, they could see Ghost standing tall and unscathed.
"What?!" Invel cried out in shock.
Gammaizer Liquid turns its body into a watery liquid as it slithers to Ghost and wraps itself to the White Rider.
"Observe. Commence analysis." Gammaizer Liquid says.
Ghost then summons his Gan Gun Saber in Naginata Mode.
"Human potential…" Ghost started to say.
"Sensing threat."
"...is infinite!"
"Evade."
Gammaizer Liquid then removed itself from Ghost as the latter activates his finisher.
INOCHI DAI KAIGAN!
Ghost charges each weapon's bladed end with swirling blue energy before he presses the trigger on its handle. Ghost then gave one power slash at the Gammas in front of both blades in the form of an Infinity Symbol.
YOROKOBI STREAM!
The Gammas tried to hold back the powerful slash but were eventually hit by the blast seemingly being destroyed.
~/~
Hours later after saving everybody from the dream world, Ghost in his Mugen form was now facing Gammaizer Liquid and Gammaizer Fire.
The Gammaizers that were absorbing from above and took the form of Animus fired energy at Ghost around him as the White Rider fought off Gammaizer Liquid and Gammaizer Fire. Ghost then gave an energy push at the two Gammaizers pushing them back.
"Eliminate." Gammaizer Fire fires a fireball from its chest.
The fireball hits Ghost engulfing him in flames but Ghost shrugs the flames off riding the fire.
"Purge." Gammaizer Liquid let out a rope made out of water wrapping it around Ghost's neck.
Ghost powerful aura eliminates the liquid rope. Gammaizer Fire started to fire multiple fireballs at Ghost but the latter knocked those fireballs away with his hand. Ghost then proceeds to activate his finisher.
CHOU DAI KAIGAN!
A rainbow-colored infinity symbol appeared behind Ghost as he began to absorb the attacks from a Gammaizer Fire to cover his right arm in rainbow energy.
MUGEN! GOD OMEGA DRIVE!
Ghost then delivers a Rider Punch powerful enough to destroy the Gammaizer permanently. Ghost then turns his attention to Gammaizer Liquid.
Ghost pulls the Detonate Trigger of his Ghost Driver, activating another finisher with a rainbow-colored infinity symbol appeared behind once again.
"Human potential is infinite!" Ghost exclaimed as he readied himself as he then pushed the Detonate Trigger.
"Purge."
CHOU DAI KAIGAN!
"Eliminate." Gammaizer Liquid fires water balls at Ghost but the Rider is protected by an invisible shield.
Ghost then proceeds to float up into the air.
MUGEN! GOD OMEGA DRIVE!
Ghost performs a Rider Kick imbued with the emotional power of his 7 friends that manifest together as rainbowed energy.
"Eliminate."
Gammaizer Liquid kept firing water balls at Ghost to anvil as Ghost kicked through the Gammaizer. Gammaizer Liquid changed back to its original form before being permanently destroyed.
AN: You guys must be wondering why there are characters from different stories well I decided to use all of Hiro Mashima's work and combined them into one world, so you'll see some characters from Fairy Tail, Rave Master, and Edens Zero. But the main three Riders are; Haru Gurori as Ghost, Shimon Mikazuchi as Specter, and Arius as Necrom. So if I ever come back to this world you will these characters from Mashima's work.