Silence swept the quiet streets of Futo City late at night. The windy city had seemed this way ever since the legendary protector of this place, Double, had stopped the spread of the mysterious Gaia Memories, which were able to turn the user into a Dopant, using the rider's own Gaia Memories. Peace seemed to go wherever it needed to in Japan, as many Riders had answered the call to save their world from danger.

However, this night was unlike any before, as a mysterious plot was about to unfold.

Looking out onto the city, a young man with black hair wearing a green striped shirt sat on top of the detective office where he worked. The man thought about all that he had been through over the past few years. He had been through many cases involving the Gaia Memories alongside his partner, but had that been worth losing his family for?

"Hey! Phillip!" shouted another man from below the building. This man wore a black suit and a detective's hat, which sat on top of his brownish-black hair.

"Oh, Shotaro. I'm just looking up at the stars," Phillip responded.

"Well, we need to go," Shotaro stated, "I got a call that said something mysterious is going on near Futo Tower."

After getting down from the roof, Phillip hopped onto the back of his and Shotaro's motorcycle, the HardBoilder, and jetted toward the tower in the center of the city. Once there, they saw multiple humanoid beasts running around wreaking havoc around the tower.

Shotaro sighed and shook his head. "Looks like peace never really lasts." With that, the two detectives ran toward the creatures and began to fight. However, they soon outnumbered them and it was too hard for them to fight on their own.

Suddenly, two more figures appeared out of nowhere. One had brown hair that fell all over his head, and the other had black hair and styled it in an American fifties style.

"Glad we could join the party!" the black-haired one shouted.

"Eiji! Gentaro! What are you two doing here?" Shotaro asked.

"Us riders have to stick together, remember?" the brown haired one, Eiji, stated. With that, he revealed a rectangular shaped device with three circle shaped slots on it. Gentaro also brought out a device with 4 switches on it and a handle, and four slots for placing something inside them.

Shotaro and Phillip nodded to each other and Shotaro brought out their device as well, which was a device with 2 slots on it. Together, the 3 placed the devices to their waists, causing a metallic band to come out from the side of each and wrap around each of them to create a belt. Another version of Shotaro's belt also appeared around Phillip's waist.

Together, Shotaro and Phillip revealed a small flash drive-looking device. They each clicked a button on each device and they spoke. "Cyclone! Joker!"

Eiji himself revealed 3 medals which he placed in the slots of his belt, while Gentaro flipped the four switches on his belt, which caused an electronic voice to count down. "3, 2, 1!"

"Ready, everyone?" Eiji asked.

"Ikuze! (Let's go!)" shouted Shotaro. Together, Shotaro and Phillip placed the devices in their belts, in which Phillip's disappeared from his and appeared in Shotaro's. Eiji also reached for a circle-like device strapped to the side of the belt.

"Henshin!" the heroes shouted, activating the action to change into their rider forms. Shotaro moved his hands to push the two sections of the belt apart, causing black and green particles to fly at him. "Cyclone! Joker!" his belt exclaimed. Beside him, Phillip collapsed to the ground, his mind transferring into Shotaro's body.

Eiji moved his scanner across his belt, making a bell chime after it passed over a slot with a medal in it. He was then surrounded by medals that moved and rotated as the belt shouted "Taka! Tora! Batta!" When the medals rotated to show an eagle, a tiger, and a grasshopper on it, the medals fused together and moved towards Eiji, his belt singing "TaToBa! TaToBa, TaToBa!"

Meanwhile, Gentaro pulled on the level on the side of his belt then thrust his arm into the air. The belt suddenly started releasing smoke as he transformed.

When the transformation was over, three armored heroes stood in front of the creature. The one on the left was split down the middle with a gray metal line, with green colored armor on the right side and black colored armor on the right, with two red lenses for the eyes. The one of the right was dressed in a white with orange lines on the torso of his armor, and the helmet was rocket shaped with two orange eye lenses. The middle hero was dressed in three colors. He had a red helmet shaped like a bird, a yellow torso with tiger claws folded back away from his hands, and green pants. Each had their own belt still on their waist.

"Saa, omae no tsumi o kazoero! (Now, count up your sins!)" the rider on the left, Double, shouted.

"Uchū kitā! (Space is here!)" the rider on the right, Fourze, exclaimed.

"Why don't I have a catchphrase like that?" the middle rider, OOO, muttered.

Together, the three Kamen Riders charged into the fray to fight the beasts. Double used multiple punches and kicks that seemed to use the wind to hit them. OOO activated the Tora claws on his arms to slice up some of the creatures. Fourze used his combat techniques, and occasionally pulled out a strange device known as an Astroswitch, placing it into one of the slots and activating it, with the belt shouting "Launcher on!" and a missile launcher appearing on his right leg, which he used to shoot missiles at the creatures.

After a bit of fighting, the trio had defeated all of the creatures, who reduced to dust. This was rather confusing to the riders. Suddenly, they heard slow clapping in the distance. A man with blond hair walked up toward the heroes. On his waist was a belt that looked similar to Double's, but one slot was not present on the left side of the device.

"Good show. Good show, my friends," the figure sneered.

"Who are you?!" Double demanded.

"Me? I'm just a simple man passing through. You seemed to do a good job facing my minions." With that, he revealed a Gaia Memory that was grey and white. He clicked the button, which caused it to shout "Clone!"

"You sent those things at us?!" OOO responded.

"Why, of course. But, that's not the only trick up my sleeve," he replied as he placed another Gaia Memory into his belt and activated it. "Henshin," he stated darkly. The driver shouted "Chronos!" as yellow-gray particles flew toward him, turning him into a gold-armored warrior and producing a shock wave that knocked the three riders to the ground, de-transforming them.

"What… what are you?" Eiji exclaimed.

"I am the newest ruler of this world. Master of Dimensions! I…" the evil rider said, "am Kamen Rider Chronos." With that, 4 portals opened behind Phillip, Shotaro, Gentaro, and Eiji, sucking each of the heroes into one portal, where they disappeared from sight.

Notes: I've always wanted to take an attempt at a Kamen Rider/Super Sentai Crossover. I personally thought the idea would be great of Riders Double, OOO, and Fourze teaming up with the Gokaiger. Note that I live in America, so this may not be accurate to the show, but I will try to keep them acting as japanese to the show as possible.