Disclaimer: Not mine.

Author's Note (Rinshi):

For starters I must say that this idea was born alongside a friend, both of us are a fan of Nasuverse and the Indexverse.

We noticed a great lack of crossovers for both so we decided to create one. There are some completed chapters already that I'll be posting weekly.

Without saying more, let the show begin!

Prologue

Shirou was certain that the Root had something against him. Or, maybe it was the existence of Emiya Shirou as whole that was a profound insult against the Root. So much so that he became a personal chew toy that evolve from being insulting to entertainment.

"A piece of entertainment to hilarious to let go" thought Shirou Emiya as he carefully placed the box with all his worldly possession in his new apartment. Opening the window to let some fresh air in, the sight of the expansive city scape of Academy City filled him.

The strangeness of it all still lingered in his mind and to think it was only a couple of days ago that his life was still in the norm, hunting and ending Dead Apostles. After all, he was considered as the Second Magus Killer.

Shirou still regretted not realizing in a timely manner that accepting any request from Zelretch was akin to suicide. The mission was as simple as it goes. Hunt down the Dead Apostle Fernand Kreiven, take back the artifact he stole from Zelretch and go home. Simple.

He should have seen the figurative nail to the wall when through happenstance the member of the Church targeting the same Dead Apostle specifically asked him for help. Added to the fact that the Church agent was none other than Caren Ortensia, well, he should have seen it miles away.

Regretting it all the same, Shirou should have known that his life wasn't so simple. Even when the situation screamed disaster. By the time they reached the forest in India looking for the Dead Apostle, it was too late to reconsider. The fact that Kreiven was named a possible candidate for one of the available seats between the Twenty-seven Dead Apostles Ancestors was not even worth mentioning at this point.

Hunting for a Dead Apostle in India raised several flags at the back of Shirou's mind as a Dead Apostles sense of superiority would naturally reject establishing a power base away from any civilized society.

And there was precious few intel on Kreiven, whose profile dated back to when he was a magus. The cautious and discrete manner in which Kreiven conducted his thaumaturgy research before using magecraft to turn himself into an undead seemed to continue to influence his actions till now.

Kreiven stealing an artifact belong to Zelretch was completely against his modus operandi. It seems that Kreiven was done hiding, willing to face the world with the artifact he stole from the Wizard Marshal and unlocking the mystery of the Second Magic.

Facing a horde of ghouls wandering around the forest, it seem certain that the vampire was already alerted to their presence. With the team being only two of them with Caren only had received Basic Combat Training as any other members of the Church it was unlikely they would be able to clean out the horde without calling for backup.

But with her Masochistic Pneumatic Automatism Diathesis, an unusual property inherited from her mother, it allowed her to "detect" any nearby person has been possessed. With the number of ghouls too large to clean out but enough to be a hindrance which followed the Dead Apostle's profile, Shirou and Caren decided to bypassed the ghouls and directly engage the Dead Apostle.

By the time they reached Kreiven, he had manage to partially activate the artifact. Cornering him behind one of the rooms in his hide out, the plan was for Caren to keep him occupied with the Shroud of Magdalene while Shirou would trace one of his Noble Phantasm he possessed and engage directly.

However as they breached the room and were about to engage, the Apostle had reached a point of desperation that he decided to activate Zelretch's artifact.

Within ensuing explosion, the last thing Shirou and Caren saw was a multicolored light of the kaleidoscope.

When they opened their eyes, they found themselves in another Japan, in a city filled with windmills.

Somewhere in the Clock Tower, London. The old bloodsucker known as Kischur Zelretch Schweinorg was once again trolling his favorite student, Rin Tohsaka.

During the last two years under his tutelage, her progress steadily decline when she ended her relationship with the young Emiya. It was as if her enthusiasm had disappeared. The original spark she had was gone and the only reason that Emiya was still registered as her apprentice was to give themselves a reason to talk during reports.

"Hey old man, what kind of mission did you send Shirou to?" Rin asked with a bit of hesitation in her voice, unable to keep her interest of her former lover's life hidden in bay.

"Hmm?" the Old Man of the Jewels responded, noticing that his apprentice had just asked a question. "Ho! I sent him off to recover one of mine artifact which has been stolen."

Lifting an eyebrow Rin asked inquiringly, "A stolen artifact of yours? It must be something powerful if you want to recover it." Knowing Zelretch who was one of the most powerful entities in the world and the holder of the Second Magic, anything created by him must be capable of creating miracles of incredible scale.

"Nah" was the careless response from the old man, "to tell you the truth, I don't even remember what it exactly does. It was one of the first prototype to my Jewel Sword but there was something wrong with it. I can only remember that to use the sword, it had a price aside from the prana required to activate it. You know, the laws of equivalent exchange and all that."

Rin's eyebrows twitched, "If you don't know what it does, and if it was a failure… then why recover it at all?" She asked with hint of anger lacing her voice.

"HAH! Simple! Failure or not, it is mine and I do not like others playing with my stuff" he proclaimed as if it was command from god.

The Head of Tohsaka could only sighed. She had already gotten used to her master's shenanigans. In fact, the Old Man loved to troll her because it was "fun". To send a magus capable of tracing the most powerful Noble Phantasms of the world just to get his toys back was just the things he would do.

Rin only hoped that Shirou would come back alright. But knowing his luck it was probable that he would end up in another crazy situation.

By some odd reason, she felt a shiver run up her spine. Given that it happened often when she was near the old bloodsucker for so long, she just dismissed it.

But unknown to her, Fate's gear had already put Shirou Emiya into another crazy situation created for Akasha's amusement.

Translators note:

Original: s/8464598/1/To-Aru-Fate-Caren

Yes there already is a translation project underway but it seems the translator is AWOL so I decided to pick it up. Anyone who wants to read ahead feel free to use Google.

This is not a straight copy paste translation using Google translate and surprisingly it's taking some time to adapt it properly in a structure and format that would read well in English.

Bit of a warning: I don't speak a speck of Spanish. It's heavily edited and not a one-to-one, 'pure' translation. So some meaning will probably be misinterpreted.

Note:

All plot and story related inquiry should go to Rinshi.

All English grammatical error should go to me.

All Spanish-English translation error is due to Google.