Disclaimer: I don't own Kamen Rider or Samurai Jack.

AN (EDIT-4/27/2017): I know it's weird having a crossover with Samurai Jack and Kamen Rider, but seeing how in cartoons anything can happen, I decided why the heck not. I was pretty much inspired to do this after reading Kamen Rider Chrome's Ai Yori Aoshi: KAMEN RIDER RONIN. When I saw samurai Riders, I couldn't help but think of Samurai Jack! It's a pretty cool show in my opinion. Therefore I made this.

Now enough of me babbling, let me show you!

Raika out.

PS: Oh yeah, this episodes takes right after Season 3 episode 7, "Jack and the Traveling Creatures." Thought I should mention that, so you can watch the episode before reading this fic to not cause any confusion.

Long ago in a distant land, I, Aku, the shape-shifting master of darkness, unleashed an unspeakable evil! But a foolish samurai warrior, wielding a magic sword, stepped forth to oppose me! Before the final blow was struck, I tore open a portal in time and flung him into the future, where my evil is law! Now, the fool seeks to return to the past, and undo the future, that is Aku!

Jack's vision was blurred once he opened his eyes. He rubbed them and his vision became clear, staring up at cloudy sky. 'Where am I?' he asked himself as he sat up.

It was then he noticed that something was off. The top half of his kimono was torn, revealing his entire upper body that covered in scars and bruises. Jack noticed his hair was down for he didn't have his pin that kept it up. 'What happened to me?'

It was then Jack remembered. His fight with the Guardian of the time passage. It ended disastrously. Jack could remember the blows he received from the mighty blue-skinned warrior. "I lost," he sadly stated.

There were battles that Jack lost, but this one had more of an impact. He was so close, oh so close, to achieving his goal. It was right there in the palm of his, but it slipped through his fingers. Anger began to build up in Jack. "RAH!" he screamed as he slammed his hand onto the ground.

BONK!

"Ouch!" Jack winced in pain as he felt his hand hit something metallic.

He looked down to see what his hand had hit. It was a strange, white buckle. The buckle itself was unusually large and rectangular with a slot on the right side of the buckle, while there was a thin slit on the left. The buckle had an square opening in the center but that was covered by a red, transparent window. Right next to it was Jack's sword. He picked his sword off the ground and sheathed it into his belt before looking at the buckle. "What is this?" Jack asked himself as he picked up the strange buckle.

As he picked it up, Jack could feel paper on the back of it. He flipped the buckle around to reveal a note taped to the buckle. Jack ripped of the note. It read:

Samurai Jack,

If you reading this, then it means you have survived our encounter. It was not my choice, though, to let you live, it was someone else. That same person wishes for me to give you this. This is the Shogun Buckle. It was made a long time ago by the same forces who forged your sword. They made this for the wielder of your sword. To not be deceived by the looks of it. Though it may be a buckle it can give you tremendous power so you may defeat Aku. To activate it, just slide your sword through the Shogun Buckle. But keep in mind that the Buckle may be used only once. Use it in times of great need.

Signed,

The Guardian.

Jack could only raise an eyebrow at that. The Guardian, the same one who beat Jack up to prevent him from entering the time passage, left him this. "Why would he do that though?" Jack wondered aloud as he stared at the buckle, now dubbed the Shogun Buckle.

Out of curiosity, Jack placed the Shogun Buckle on his stomach. He was taken surprise when a golden belt strap shot out of one end of the Shogun Buckle and wrapped around his waist, fastening it on. 'Incredible!' Jack thought.

Jack remembered about the letter saying that he needed to activate the Buckle's power by sliding his sword it. He drew his sword and placed before the slot on the right side. He was about to do it, but Jack froze. He also remembered what the letter said: It could only be used once.

Jack sighed as he removed his sword from the Shogun Buckle and sheathed it. He then grabbed his buckle and ripped it off of his waist. Jack stared at it for a moment before walking off. It would have be needed some other time...

'Now would be a good time to use it!' Jack thought as he ran through Aku's lair.

Months passed since he obtained the Shogun Buckle. He traveled across the land, honing his sword skills, so he would be ready to fight Aku. As he traveled, he face more and more of Aku's minions for it seemed their numbers had been increasing for dozens were sent after Jack instead of a few. Jack returned to Aku's lair, this time ready for anything the demon sorcerer was going to throw at him. However, the lair made of fire was abandoned. No guards, no droids, no minions whatsoever. Jack realized it was trap, but it was too late for Aku himself appeared.

Jack first tried to fight Aku, but he was faster and more cunning than Jack remembered for Aku tried firing blasts at him before morphing into almost every single threatening creature that Jack faced. He ran and ran for life like never before, dodging every attack that Aku threw at him. However, it was futile for he ended up at a dead end. Jack turned around to see Aku laughing as he took his true form. "What will you do now, samurai!" he laughed. "There's no where to run! It's the end for you!"

"No, it's not Aku!" Jack shouted back as he reach into his kimono to pull out his Shogun Buckle. "I have this!"

"What are you going to do with that, Samurai!" Aku laughed.

"This!" Jack declared as he placed his Shogun Buckle onto his waist and the belt fastened it on.

Aku stopped laughing at the sight of this. Jack smirked at the sight of Aku's face as slid his sword into the buckle. The center of the buckle glowed brightly with white energy, blinding Aku. When the light died down, Aku turned and his eyes widen at what he saw before him. "WHAT!" he shouted.

Jack now wore white and golden samurai armor over his black bodysuit. He had a golden chest plate with his crest etched in the center as well as golden armor on his upper legs and arms. Jack had white gauntlets and boots as well as white shoulder pads with three black tiger stripes on each. A piece of white fabric with black trimmings hung from his belt down to his knees, and it had three golden stripes on it as well, which were golden instead of black. Jack's white helmet resembled a damiyo's with three tiger stripes on the top and a pair of golden horns protruding from the forehead. He wore a black face plate with two red eyes over his own and a white mouth plate.

Jack had just turned into Shogun.

"This can't be!" Aku shouted. "How did you get that kind of power!"

"Somewhere, you'll never know, Aku!" Shogun declared, pointing his sword at the demon sorcerer. "Now come and get me!