Disclaimer: I do not own Fate/Stay Night or Kamen Rider Saber. F/SN is owned by Type-Moon and KRS is owned by Toei.
It's been a few years since Touma moved to Fuyuki. Even though he has retired from his swordsman duties, he was here to investigate the mysterious fire that happened 10 years ago. The fire that has killed hundreds, if not thousands, of people. Touma was still a swordsman at the time, but he couldn't make it to Fuyuki due to some problems in Wonder World. He could have at least minimized the casualties. Furthermore, he could have stopped it with the power that he currently has. But Touma decided not to think about it any further since it was in the past. So he decided to investigate how it started. Now Touma has opened another Fantastic Bookstore Kamiyama to continue his novelistic career while being a part-time Japanese teacher at Homurahara Academy.
Touma was currently having a talk about some important matter with Rintaro, one of his friends back in Touma's day working with Sword of Logos, an organization dedicated to protecting humanity.
"So Rintaro, what brought you here?" Touma asked.
"It's about a war that will be happening here, in Fuyuki." Rintaro answered as he opened up a small bag.
"A war? What kind of war? I've been living in Fuyuki for a few years now and everything seems peaceful, it's not like a war can happen out of nowhere." He said as he took a small sip of his tea.
"Well, I assume you do know about the fire that happened here 10 years ago, correct?" Rintaro asked while taking out a book from the bag. The book's front cover was a portrayal of a grail, while the back was the Sword of Logos symbol.
"Yeah, that's the reason why I moved here in the first place. To investigate the cause of it."
"Then let me tell you something. Recently, Sophia-san found a book about the Holy Grail War that happened in Fuyuki 10 years ago, along with the other wars." Rintaro said, handing Touma the book.
Touma was silent for a while. He slowly takes the book from Rintaro and inspects it. After a while, he finally started talking again. "Other wars? How many of this Holy Grail War were there?"
"Four, this one will be the fifth one."
"I see" Touma said, losing himself in his thoughts. A war? Here? And is it the same war that happened here 10 years ago? That gotta have something to do with the fire. If he were to take the case, he'd definitely find out something about it.
"Touma?" Rintaro asked, snapping Touma back to reality.
"Ah, it's nothing. Thanks Rintaro, I'll take a look at this." Touma replied.
"Then I'll be taking my leave. Thank you and good luck, Touma. If anything bad happens, just contact us, we'll be there if you need." Rintaro said, finishing his drinks and standing up from his seat.
After Rintaro left, Touma let out a sigh. Apparently, the "Holy Grail War" has been going on for around 300 years now. And it doesn't even work properly after the third one! After reading the book that Rintaro gave him, he knows that Rin Tohsaka, Sakura Matou, Shinji Matou and Shirou Emiya will be participants of the next war regardless. He can understand why Rin and Shinji would participate in the war, he just couldn't find any reason for Shirou and Sakura. Sakura was a kind girl, and Shirou reminds him of Kentou, about how both would sacrifice themselves for the sakes of others. Touma let out another sigh, thinking about how to prevent the war or at least minimize the casualties. Sure, he could destroy the grail with Haouken Xross Saber without the mud appearing, he just needed the grail to appear first. That's when an idea hit him. What if he summons a Servant and participates in the war as a Master himself?
Author's Note
This is my first time writing anything, so don't expect much. I would really appreciate it if you leave a review and help me to improve my writing. Now, that aside, I think this would be a really cool story to write based on the fact that Artoria and Touma are both literally Sabers. And yes, this is post Trio of Deep Sin Touma, so expect him to be really op.