On this day, the universe begin to undergo the most chaos it had gone. Across space and time, mayhem ensued as an unknown force had attacked them.

On this day, the most unlikely of alliances were formed. From heroes to villains, the adventure that ensued transcended both time and reality.

This...is when worlds collided.

Downtown Tokyo

Everything was going well in the streets of Tokyo. People were enjoying a rather relaxing time, and most were taking it easy.

One of those taking it easy was Sonic the Hedgehog, who was going for a morning run. Leaping of the sides of building, Sonic landed on top of a billboard and smiled at the scenery.

"Good thing we were able to fix up everything after Eggman's shenanigans. Honestly, I'm wondering where he is..." Sonic spoke, looking at the beautiful city and sun. He was about to take a few minutes to relax...

Until he heard a giant explosion in one of the city blocks. "Guess I spoke too soon." Sonic muttered, before shrugging and rushing off to the source.

Seeing robot animals made Sonic grin, as he rushed in to kick one in the back. "Whew! Looks like Egghead's back at it! Although he's definitely picked up on better designs..."

Dodging a shot from one of the machines, Sonic performed a Homing Attack on each individual robot, and saw the purple robot watching him. He positioned to target him...

...But found himself being blasted out by powerful shots. As a result, the Blue Blur resorted to dodging each shot before closing the distance, throwing out an axe kick at the robot.

But the robot was quick enough to grab Sonic's leg, swing him overhead, and slam him into the ground behind them, cracking the pavement before punching the hedgehog away, firing another blast afterwards.

Sonic looked over, and was quick to boost out of the blast's way. "Heh, not bad! You're pretty good for one of Eggman's badniks."

After a bit, the robot began to chuckle. "Eggman, you say? So that time experiment DID work..." The robot cackled, as Sonic raised an eyebrow.

"I'm not one of that old fool's minions. My name is Vile, and I'll destroy anyone in my way, including you!" With that, Vile launched an another shot, promoting Sonic to leap over.

"So Eggman's not the one launching the attack this time, huh? Eh, I'll smash you the same as I smash his toys." Sonic remarked as he blasted downward to stomp on Vile. The Reploid would however, simply use a hand to stop his foot, then slam his fist into Sonic's chest, knocking him into a building.

"Gah, a little too tough..." Sonic grumbled as he jumped to his feet and charged. He used his speed to his advantage, running circles around Vile as he attempted to shoot him, but Sonic's speed was too much for him.

But Vile wasn't a fair fighter. Being as heartless as one could be, he took aim at one of the buildings nearby, and fired a blast that split it. The screams of the people inside were heard as Sonic changed targets to saving those inside.

And with his super speed, it's not to big a hassle; he rushed in, grabbing everyone one by one and bringing them out to safety. "You okay, ma'am?" Sonic said as he set down the last one down, a young lady. "Yes.. yes! You saved my life!"

But Sonic being distracted is EXACTLY what Vile wanted. With this, he took aim before firing a laser that finally hit Sonic launching him back far, and causing the crowd to run. He tried to get up, but Vile was quick to head over and stomp on his chest.

"You know, in my time, you're a legend. But one day, you disappeared. And I think we now both know what caused that, don't we?" Vile asked as he began to charged a powerful shot. Sonic grunted as he attempted to pry the foot of him to no avail...today, Sonic fell...

...Or at least, Vile thought.

"Hadoken!"

Suddenly a energy wave struck Vile's side, knocking him away. "What...?! X, did you follow me?!" Upon looking up, however, he realized this was not the case.

It was a man who wore a white karate gi and a red headband. His name is Ryu, the one who constantly searches for opponents to fight in order to improve his fighting ability.

Looking over, Ryu walked to Sonic and gave him a hand. "You alright?" He asked, with Sonic taking it and being helped up. "Eh, I'll live."

After a few seconds, Sonic was standing again. "You're not X...yet you use his abilities...I'll gladly kill you too, human!" Vile yelled, before shooting rapidly.

But Ryu was no ordinary human. Within moments, he was weaving around the shots. Was he as fast Sonic? No. He merely timed his movements right to evade the blasts before he eventually got close enough.

When the street fighter was right in Vile's face, Ryu reeled his fist back before slamming it into Vile's chin. "Shoryken!" With that, Vile flew into the air, with Sonic running and leaping after him.

"Time for some payback!" Sonic quipped, before doing a barrage of Homing Attacks. Vile was sent barreling through the air from the damage before ultimately crashing down with a hard kick to the noggin.

With a grunt, Vile tried to stand, but Sonic quickly reeved up into a ball and performed the Spin Dash, blasting towards Vile, and tearing off an arm.

The robot yelled in agony, before adrenaline kicked in and he began to fire wildly. Sonic weaved as Ryu performed a Tatsumaki Senpuyaku to evade, and performed a harsh kick, denting his chest and knocking him into a wall.

"Damn it..." Vile grunted as he held where an arm once was. While Vile expected Sonic to do damage, he definitely didn't expect a human to be this strong...as much as he hated to do so, he knew he had to retreat.

"...Know this, you two..." Vile muttered as he slowly stood. "Just because I lost here, doesn't mean you've won. I'll return, and I'll make sure you are blown to pieces!" Vile bellowed, as Sonic rolled his eyes. "Yeah, sure. And I'm the slowest thing alive."

Sonic rushed up to punch Vile in the head, but the robot was quick; teleporting away. "Shoot, that was fast..." Sonic muttered, genuinely impressed. Dusting his hands off, Sonic turned to Ryu and walked over. "Not bad, Karate Kid. Whatcha name?"

"My name is Ryu." He responded, before Sonic began thinking. "Hey, aren't you the same person who attended that one tournament but didn't appear in the ceremony despite winning?" Sonic asked, with Ryu nodding.

"I have no desire for awards. I only attended to face opponents that can test my skill." Ryu explained, with Sonic shrugging. "Well, if that's how you want it..." He muttered. "So uh, I'll be going. Gotta go ask Tails if I can find that bot anywhere."

With him speeding off, Ryu was left to his thoughts. He felt a weird wind...what was this feeling? It was as if trouble was brewing...on a unknown scale.

Little did Ryu know how bad it would it get.