Author's Note: Before we begin, I would like to credit GhostKaiser 23 and GreyKing46 for giving me approval for making this story, and for helping me figure out how to craft the plot. I can't thank you two enough!

Advent 0: Prologue

Mere moments ago, a horde of monsters burst into the city as every reflective surface shattered. The monsters began snatching up people and eating them, but their rampage did not go unopposed. Two lone figures stood exhausted among the ruins of the city. Both clad in strange armor that had similar elements but was based on different animals. One figure wore a red suit and had a helmet with large red bug eyes concealed by a grill with the symbol of a dragon on top of it. The figure standing next to him wore a dark blue suit with a bat motif. One common element that both figures had were the silver belts with what looked like a card deck held at the center. These were Kamen Riders Ryuki and Knight. And they had just exterminated the last of the horde. However, the city was far from saved.

"We did it, Ren." Ryuki panted as he removed the deck from his belt with Knight following suit.

As the armor shattered away in shards, the man underneath was revealed. He had red-brown hair and was clad in a blue jacket and jeans with white sneakers. This was Shinji Kido, the civilian identity of Ryuki. The man next to him, Ren, was Knight's civilian identity. He was clad in black clothing and bore a tired expression just like Shinji.

"Even going Survive, that was unbelievable." Shinji panted as he looked up to the sky. His expression turned somber as he reflected on the events that had led up to this.

Shinji had accidentally stumbled into being a Kamen Rider and found himself in a battle, no, a war between the riders over a wish. A war fought in the Mirror World, a dimension that lay behind every reflective surface where ravenous creatures, the Mirror Monsters, dwelled until they decided to feed upon the people of the city. Upon entering the Rider War, Shinji tried to band the Kamen Riders together to fight the monsters and save humanity. Unfortunately, most of the riders cared about one thing only: The wish. So many were ready and willing to fight, kill, and die for the wish that was promised for the last rider standing. But despite his efforts to stop the fighting, Shinji's own cowardice and self-righteous attitude only made things worse. And it was upon reflecting that Shinji realized a painful truth: He had failed. But if there were any silver lining to this situation, it was that his friend Ren was still standing with him and the horde had been destroyed.

"Heh. It's funny, Ren." Shinji let out a tired chuckle. "This all began with the two of us and it ends with the both of us too. The Rider War's over, and two Kamen Riders remain standing. I guess Tezuka did manage to change fate after all."

"No, Kido." Ren said evenly. "There's only one rider standing."

Hearing this made Shinji stiffen. Throughout the Rider War, there were many times where Ren had sworn to defeat him. Despite the frequency of those threats, Ren had never followed through with them. But, if he were going to meet his end by another rider, Shinji could accept if it were Ren that did him in. A sad smile crept across Shinji's face as he turned to face Ren, and saw him falling to the ground.

"REN!" Shinji cried out as he caught his friend before he hit the ground! Upon finally getting a good look at Ren, Shinji saw he was in pretty bad shape.

"I'll help you up, and we can settle this once we're rested up and healed! If we end up in a draw, you'll clear the debt I owe you!" Shinji cried out as he tried to help Ren stand, but was stopped when Ren grasped his hand tightly.

"Kido . . . I'm glad you're the last one standing." Ren said with a tired smile. "I don't think Eri would ever look at me . . . if she knew what I did to save her. Heh. It makes sense you're the only one left. Out of all the other riders, you were . . . one of the only good people."

"No . . . no! That's not true!" Tears began to fall from his eyes at seeing his friend's life fade before him. "You were a good person too, Ren! You were more of a hero than I ever was! You didn't hesitate in fighting Mirror Monsters, and you never held back when you fought against monsters in human skin! If anyone could be called a hero, it's you!"

"You really are my only friend . . . "Ren chuckled weakly.

"Ren! Come on! Hang in there! You want to see Eri one last time, don't you?!" Shinji pleaded as he shook Ren in a vain effort to keep him alive! "Ren! REN!"

"Our debt's . . . even." Ren said with a smile as his eyes closed for a final time.

Shinji wept as he kneeled over Ren's lifeless body and arranged him into a coffin position before placing Ren's advent deck on his chest as a gesture of respect. As he got to his feet, Shinji looked around at the ruined city before staring down at the ground in shame.

"Congratulations." A voice called out. Shinji whipped his head up, and was completely shocked to see the Rider War's mastermind, Shiro Kanzaki. "The last rider standing is you."

"Kanzaki!" Shinji exclaimed! He was about to reach for his advent deck, but stopped himself. "There's no point in fighting you. The Rider War is over. And Yui . . . Yui is gone too."

" . . . I know." Kanzaki said. A rare sight of emotion on full display.

"I'm . . . sorry for your loss." Shinji said sadly. "If you'll excuse me, I'm going to try and pick up the pieces and see who I can help."

"But don't you want to claim it?" Kanzaki asked.

"What are you talking about?" Shinji asked.

"The wish." Kanzaki answered simply. "You are the last Kamen Rider standing. And as per the Rider War's rules, the wish is yours."

"You . . . you're not serious, are you?" Shinji asked in disbelief. "The time limit should be up! You said that the Rider War had to finish by Yui's twentieth birthday! Last I checked, that's today!"

"But the day isn't over yet." Kanzaki replied. "Meaning that the wish is still able to be claimed."

Kanzaki reached his hand out, and an orb of light materialized in front of him! Its soft white glow illuminating the gloom that had hung in the atmosphere. As Shinji stared at the orb, hope began to swell in his chest.

"Now then, Shinji Kido." Kanzaki said as he floated the wish over to Shinji. "What do you wish for?"

Shinji stared at the wish in contemplation. It would be so easy to just wish that none of these horrible events had ever happened, but he knew that would only fix so much. It was then that Shinji began reflecting upon the choices he'd made and his time in the Rider War. There were so many things he could have handled better if he hadn't been so self-righteous, and tragedies he could have prevented if he weren't such a coward. He'd been praying for a second chance, and now it was right in front of him.

"I wish that I'd handled things better. That I wasn't such a coward!" Shinji declared as he grasped the wish with both hands! "I WISH THAT I WAS A TRUE HERO AND STOPPED THIS STUPID WAR!"

"I would say that's a wish Yui would be proud of." Kanzaki said with a sad smile. "I truly do hope that things will be different the second time around."

Shinji nodded as his whole world was consumed by light as the wish shattered! As the wish worked its magic, Shinji smiled as he closed his eyes. The Rider War would soon begin again. And Shinji didn't know what changes he might encounter in his next life. However, one constant would remain. The Rider War's most consistent rule: If you don't fight, you don't survive!