A young man going by the name of Y/N was making his way to the outskirt of Fuyuki City, his hometown. Y/N a 17 years old young man with emerald eyes and golden hair was accompanied by a young woman with a similar appearance. To passerby the two of them looked like twins and they weren't far from the truth as the two of them were indeed brother and sister but they weren't twins.
"Y/N?" the woman spoke.
"What is it, Mordred?" Y/N responded.
"Don't you think that, that bastard invitation is a trap?" Mordred asked her tone a mix of excitement and worry.
"I'm certain it's, but he doesn't expect what we are going to do. I mean sure he is the King of Hero but is it going to stop us, onee-san?" Y/N replied as equally worried as he was excited for the fight that was coming.
"No, it won't after all we're the children of King Arthur Pendragon." Mordred responded her worries gone and completely replaced by excitement and anticipation.
"That's true." Y/N started before he continued "Hey Mordred?"
"What is it?" Mordred question her younger brother.
"I would have swear that you would be more troublesome to deal with when summoning you that night." Y/N stated.
"Frankly, if not for Father words that night and the bonding time we had while training inside your's and your father's dimension, I would have probably killed you as someone who stole what was rightfully mine." Mordred replied.
"That's what I imagined. Well seems like we are here, ready to give the King of Heroes a royal beat-down, Knight of Treachery?" Y/N asked his sister in a serious tone.
"Of course, I am Prince of Knights. The question is are you?" Mordred replied in an equally serious tone.
"Man, the nickname Lancelot gave me stuck didn't it. And yes I am ready, sis." Y/N responded.
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"Well, if it isn't the Knight of Treachery and her brother the Prince of Knights." said a red eyed, blond haired man in an arrogant tone.
"Where you expecting us to flee from this fight, Gilgamesh?" Y/N responded with deadly cold voice.
"No, not really I'm just getting amused because tonight I finally will have my revenge on your faker of a father when the two of you will lie dead on the ground." Gilgamesh replied still as arrogant as ever.
"The only one who is going to die is you, bastard. What you did to Father can not be forgiven so prepare yourself." Mordred yelled at Gilgamesh as her armor and her blade Clarent materialized.
"You think you two can beat me? Ah! You're fools even if you two took down the other servants in less than a week it has been three month since this sixth Holy Grail War began, do you really believe you stand a chance?" Gilgamesh laughed at them, his arrogant tone present as ever.
Gilgamesh expect a rather harsh comment from one of the two Pendragon brats as he sometime called them, but instead he had to dodge multiple swords and spears that were launch at him by Y/N's Unlimited Blade Works.
'Tch! That damn Faker's power.' Gilgamesh internally raged, he despised that move remembering all too well how he was killed by Y/N's father Emiya Shirou who wielded that same power. Gilgamesh knew better than to underestimate those two both were children of Artoria Pendragon, the King of Knights, so he didn't hesitated one second and willed his armor to appear on him as well as willing Enki his golden sword to come out of the Gate of Babylon.
Not even a moment after, Gilgamesh had equipped his armor and split Enki in its two halves, he was attacked by the two Pendragon. Mordred attacked him from his left while Y/N attacked from his right wielding Artoria Pendragon first blade, Caliburn.
The fight lasted for hours, Gilgamesh was often on the defensive because of Y/N's and Mordred's tactics. Mordred would often attack him head-on as Y/N would use the powers of Unlimited Blade Works to destroy the weapons that Gilgamesh was launching from his Gate of Babylon.
On other occasions Y/N and Mordred would attack together forcing Gilgamesh to solely rely on Enki to fight both of them, which wasn't helped by Y/N tendency to quickly alternate between Kanshou & Bakuya in their Overedge form and Caliburn, The Golden Sword of the Victorious.
Gilgamesh was both frustrated and impressed by this fight for various reasons. Firstly the Pendragon brats fought without exchanging words or instructions between one another even though it was barely three month since Mordred was summoned, their teamwork was perfect.
Secondly while the Faker's son usage of Unlimited Blades Works was far more precise than his father no doubt in the King of Heroes mind the result of the child training with the other two woman he killed the night Y/N summoned Mordred and Arturia died.
The third and final reason that with their combined efforts those two brats had nearly emptied the King's Gate of Babylon, a feat only achieved by his one and only friend Enkidu.
"Well, well you two truly deserve your titles but this is the end for the both of you, the Holy Grail is mine and mine only." Gilgamesh stated during a small moment of respite in the three fighter fight.
"That remain to be seen." Y/N replied as Mordred charged toward Gilgamesh.
"Enkidu!" Gilgamesh yelled. Chains erupted from the golden portal of the Gate of Babylon trapping Mordred and allowing Gilgamesh some time to prepare his next attack.
Gilgamesh took his twin golden swords and fused them into a bow, the true form of Enki, and he started to intone a chant "Behold! The inferno of destruction fills the heavens! Come forth! The Surge of Utnapishtim! -"
Y/N knew full well that Gilgamesh was preparing himself to unleash one of his noble phantasm, thinking quickly, he unleashed a barrage of powerful swords with his Unlimited Blade Works to free Mordred as he summoned his black bow in his left hand and Caladbolg in his right.
"This is what it means to destroy the W..." Gilgamesh continued his chant before he was interrupted by the now flying Caladbolg, while the Fake Spiral Sword missed him by a few centimeter, he could only stare as it destroyed the upper part of his bow.
"You damn mongrels, how?! How could you destroy Enki?!" Gilgamesh yelled as he finally lost his temper. "You now what it doesn't matter, I'll kill you no matter what!" the King of Heroes continued.
"Y/N, we can't go at it any longer, it's now or never." Mordred said/yelled at her brother who stood beside her.
"I know, I'll unleash both Excaliburs while you use your Noble Phantasm. I've already strengthened it with two command seals." Y/N replied. Shortly after he said that two sword one of black and red color and a second one of blue and gold in color appeared in his hands. These two swords were the Swords of Promised Victory Excalibur and its darker counterpart Excalibur Morgan.
Y/N wielded Excalibur in his right hand while Excalibur Morgan was firmly hold in his left hand, both swords were engulfed by a blue aura of mana, while Mordred's sword was engulfed in a red aura of mana. To any outside observer it was obvious that both party were aiming to destroy each other in this lone and final strike as they both held their most powerful weapons in their grasp.
"I shall offer this one strike as the ceremony of separation!" Gilgamesh was the first one to start powering up his noble phantasm as he held Enuma Elish, also known as Ea, in his hands before he was quickly followed by the two Pendragon.
"Ex- / Clarent Blood -" Y/N and Mordred started to power up their own noble phantasm.
"I speak of the beginning. Heaven and earth are divided and nothingness celebrates Creation. My Sword of Rupture rends the world ap..." Gilgamesh continued to prepare Ea before he was interrupted by the Pendragon.
"-CALIBUR!!/ -ARTHUR!!" Both Pendragon unleashed their Noble Phantasm. The three beam of red, white and black light fused together to form a single beam of mana that hit the King of heroes head on, the attack powerful enough, despite its casters state, to mortally wound the King of Heroes.
"How?!" Gilgamesh asked between cough of blood.
"You underestimated us." Y/N started.
"You thoughts that we were lucky when we dealt with the other servants." Mordred continued.
"But let us tell you one thing before you die, it wasn't luck it was pure skills." Mordred and Y/N stated in unison before both of them plunged their swords into Gilgamesh body finally killing him.
"It's finally over, I can't believe it's finally over." Y/N spoke before falling on the ground from exhaustion, Mordred followed soon after.
"Yeah, little bro, the sixth Holy Grail War is over. So what will you do with the Holy Grail?" Mordred responded.
"I'll destroy it permanently, we only need to look at the previous Holy Grail War to see what could be the consequences if some power crazed maniac came into possession of it." Y/N replied to his sister question.
"Yeah, I guess you're right." Mordred spoke a little saddened.
"Don't be sad sis, even if the grail is destroyed we will one day see each other granted it wouldn't be before quite sometime." Y/N said half-jokingly.
"Stop those stupid jokes of yours, we have a grail to deal with." Mordred stated.
"Yeah, let's go." Y/N said his tone held sadness as he knew that once he destroyed the Holy Grail, he wouldn't be able to see his sister before the time of his death.
The two Pendragon stood in front of the Holy Grail which had materialized itself a few meters away from where Gilgamesh body once laid before it disappeared in particle of light. Y/N was about to strike the grail with Excalibur before he was stopped by Mordred.
"Y/N, please wait there something I want to say." Mordred stated.
Y/N turned toward his sister before silently inviting her to continue. "I know we only have been together for about a month and that I was somewhat cold toward you for most of it but I want you to now that as your sister I truly love you, so please take Clarent with you." Mordred spoke with her eyes locked with her brother's own.
"Don't worry sis, even thou you didn't say it, I saw in the way you looked at me that you cared. I accept your gifted and I want to know that even if didn't gave me Clarent I would still remember you." Y/N responded.
Mordred eyes started to water and Y/N was asking himself if he did something wrong but he got his answer when Mordred did something he thought she would never do, she hugged him and Y/N after his shock passed hugged her back.
"Goodbye brother" Mordred said as the two Pendragon broke their hug.
"Goodbye sister." Y/N replied before striking the Holy Grail with Excalibur causing a powerful explosion which send Y/N flying to the ground, before he blacked out.
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"Ugh." Y/N groaned as he finally waked up from his sleep. It took him a few second that he wasn't in the abandoned building were he thought Gilgamesh with the help of his sister. Quickly taking in his surrounding he saw that he was in a bedroom with blue and white painted wall that contained a large bed, a closet with a full body mirror on one of it's door, a TV stand with a 27 inch plasma wide screen TV and a Xbox as well as a Playstation, the bedroom also contained an old oak desk with numerous drawer as well as a laptop on top of it.
Y/N took the chance to look at himself in the full body mirror and he was relieved to see that nothing had happen to him he still wore his armor and he quickly willed it away using his thaumaturgy. As his armor disappeared in particle of light inside his Unlimited Blades Works, he already knew that Clarent his sister sword was safely inside alongside his mother's blades and his father married swords.
Searching for an answer about his situation Y/N looked more closely the desk and saw an odd looking envelope with his full name written on it. Trusting his instinct Y/N carefully open the letter and started reading its content.
Dear Y/N,
You are probably wondering where you are and what happened after you blacked out, but you do not need to worry yourself about those questions will be answered in this letter.
Firstly, I wish to say that you achieved your goal of destroying the Holy Grail for good and I can guarantee you that you succeeded in your endeavor. However I must inform you that because of the mana you infused into both Excalibur before destroying the grail, you were transported to another world, you can even confirm this statement by doing a quick search on the internet.
You're currently in the town known in this world as Kuoh, its layout is similar to that of Fuyuki City so you should not be too much disoriented. The house where you are right now his yours to use as you see fit.
I also need to inform you that the Age of Gods hasn't ended yet which should allow you to use mana far more easily and far more often than before. I believe it won't take you long to realize that magi in this world use magecraft that is closer to true magic than your own magecraft but no need to worry about it, you should be able to learn and use this world magecraft without any difficulty.
As an information this world, while inhabited mostly by human, is also home to many supernatural species such as Angels, Fallen Angels and Devils which are the three faction of the biblical mythology and were for a long period of this world history at war against each other.
I believe those information should be enough for now, so I wish you luck and hope you are able to survive the world of Highschool DxD.
Sincerely, God
P.S : You're probably wondering how I manage to send you to this world I suppose? Well to make this long story short the explosion of mana had send you into a dimensional gap of sort, and I managed to send you to this world before your body disintegrated. I believe it should explain most of how I did it.
Y/N had to read the letter two more time to be sure that he wasn't hallucinating or dreaming before his mind started to think of possible scenario.
'Well, for the dimensional gap I can see how the biblical god could influenced it even thou the Age of Gods had ended as for the magic part, I practically can smell it in the air, as well as the time table for Kuoh Academy and that internet search confirms that letter claims, I better be careful to not piss off any of the factions. Well at least I have a relatively big house for myself as well as quite the amount of money, so I should be fine in the supplies department.' Y/N thought after checking the whole house.
The house he now owned was quite large with its six bedrooms on the first floor as well as a spacious living room and dining room on the ground floor and its training room in the house basement. The house also possessed a large backyard that possessed a pool as well as a large apple tree.
"Well, at least I have a house, food and I'll also become a second year student at Kuoh Academy at the end of the week-end, I shouldn't complain too much but this is going to be such a drag when those two heiress notice me and my abilities." Y/N said to himself before going back to his new bedroom to nap for a while.
'I really hate your E ranked luck, dad.' Y/N thought to himself before falling asleep on his new bed.
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A/N : Well I hope you liked this first chapter. Constructive criticism, suggestion, tips and advice are appreciated don't hesitate to put it in the comments.