Day 1 (3rd Person Pov)
Mordred was leading everyone up a mountain, Rias's entire peerage had bags full of stuff on their backs, with Kiba and Koneko leading them with ease, Asia was close behind but only due to her having some help from Y/n, Akeno looked to be struggling but only a tiny bit
Rias and Issei however looked as though they were going to pass out any second
Rias: I'm the king why must I also train?!
Mordred: Oh stop being a whiny brat just because your a king doesn't make you special in any kind of way, you still need to train in order to get stronger otherwise you'll have no hope against Riser and his peerage
Rias: I think we would do completely fine
Y/n: Only Akeno could really do something against them to be really honest
Akeno: Aww thank you Y/n~
Y/n: Koneko and Kiba would be able to match their respective pieces but they lack other qualities, Asia here just isn't a fighter at all so don't even bother with trying to train her in anything but magic and finally you and Issei are just how do I say this
Mordred: Issei is just hopeless as for you, do you even know how to use your power of destruction?
Rias: Of course I do!
Mordred: Alright just asking no need to raise your voice hot head
Issei: You can't say that to Pres!
Y/n: *Sighs* How long do you intend to stick your dick up her ass Issei?
Issei: W-W-What?
Mordred: What a fool of a dragon
Issei: I'll show you!
Mordred: *Turns around* Show me what? You have a mid tier longinus, I have a top tier one and let's not forget I'm also part dragon as well as a Pendragon, I have all the necessary training and you have nothing
Issei: I don't care I can still beat your ass bitch!
Mordred's eyes glow red and in a second she has Clarent right at his neck
Mordred: Let me get this straight fool, we're helping you so either take this gratitude of ours or we can leave you be and watch you fail as Rias marries that good for nothing jerk
Y/n: Mordred... that's enough
Mordred: Hmph he was asking for it
Y/n: Issei
Issei: Y-Yes!
Y/n: Don't go round picking fights you can't win just because you have an alright sacred gear, it'll only get you killed
Issei: Right...
Y/n: Good... we're here
They all reach the top of a mountain and see a mansion in front of them
Issei: We're going to stay here, can we rest now?!
Mordred: Don't get your hopes up, we're going to test all your abilities once more
Kiba: How so?
Y/n: All of you, against us two
Akeno: You think you can beat us all?
Y/n: Are you doubting us?
Mordred's and Y/n's balance breaker armour appear as Mordred releases flames that make the entire place hot
Issei: What the hell?
Mordred: Like it? It's my sacred gears ability, the hotter the place is the stronger I am, right now I'd say I'm 50x stronger
Rias: You've got to be kidding...
Mordred dashes forward faster than any of the devils can register and kicks Rias's stomach
Mordred: Am I?
Rias goes flying into a tree as Kiba summons a sword and attacks Y/n who catches the sword with two fingers
Kiba: Are you not going to use Excalibur?
Y/n: What's your obsession with my Excalibur?
Y/n gives Kiba a roundhouse kick to the face then ducks one of Koneko's punches, he then leans back to avoid his head being cut off by Kiba
Kiba: I made a promise to destroy all Excaliburs!
Y/n: All? Oh right now I understand!
Kiba brings his sword down but didn't expect to hear the sound of two weapons colliding, looking down he saw Y/n holding a green spear
Kiba: What the?
Y/n: Surprised? I would be too, Rayquaza's spear of the Heavens it's said to be so strong it can pierce even the pure light from the Heavens
Issei: I want that!
Mordred: Hmph show off
Akeno: Do you not have one?
Mordred: Of course I do
In her hands materialises a white bow and a white spear
Rias: You've never used them
Mordred: I prefer swords but that doesn't leave these weapons useless
Akeno: What?
Mordred: My gear can analyze anyone's weak points and once it does my bow will automatically aim for that area
Rias: What about the spear?
Mordred: That's a secret
The weapons disappear and Mordred appears behind Akeno, she then swipes her and punches her stomach digging her into the ground, she looks up to see Rias preparing an attack with her Power of Destruction and swatted it away once she shot it
Mordred: That's useless against me
Mordred attacks Rias as her hand is covered in red lightning, as she throws a punch at her face it's then caught by Y/n
Mordred: What are you doing?
Y/n: I think they've had enough
Mordred looks over to see the beaten peerage and gives out a huff then leaves her balance breaker armour
Rias: Don't you think you went a bit overboard with the balance breaker?
Y/n: Yeah we did, but at least we know what you all need to train on
Rias: Oh really?
Mordred: Yes you need to train on everything
Y/n: *Sighs* Kiba needs to increase his base strength and endurance, he may be a knight and have an advantage with speed but that's like the only thing he actually relies on, and I'm also going to have to help him get over his problem with Excalibur
Mordred: Akeno needs a quicker reaction time, I don't even know about her spells or anything I defeated her with one punch, Rias needs to use less energy and less time when charging an attack, I defeated Akeno and sensed your incoming move
Y/n: Koneko's strong I'll give her that but she's too slow, I've seen snakes move faster no offence as for Issei well
All of them look at Issei who had been thrown through multiple tees and was hanging upside down knocked out
Mordred: We'll have to teach him the basics to even survive
Y/n: Yup
Rias: *Sighs* We're that bad?
Mordred: I wouldn't say your bad
Rias: Really?
Mordred: Your terrible, atrocious I'd say
Rias: Wow...
Y/n: Anyway you guys rest up we'll get everything ready for training tomorrow
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Day 2 (3rd Person Pov)
Y/n had Koneko wearing some weights and run round the mansion whilst Kiba was trying to punch Y/n who was avoiding every punch he threw
Y/n: If you want to get strong enough to destroy Excalibur then you'll need to hit sharper, more precise and quicker! You can't throw these wild punches everywhere!
Y/n swiped Kiba making him fell then summoned his spear and pointed it to his neck
Y/n: You won't be able to land a hit on Riser's knights if you move the way you do, come on let's try again but this time use your sword
Kiba gets onto his feet then summons his sword, Y/n twirls his spear as Kiba then dashes at him, jumping back Y/n spun sticking his hand out allowing wind to gather up behind his spear before throwing it at Kiba's feet
Kiba looked confused then felt a strong gust of wind catching him which threw him back into the forest, landing on his feet he gripped his sword tightly and dashed forward, just as he was about to reach Y/n he jumped to the side and tried to slash his stomach which was blocked by Y/n's spear
Kiba: Wait what?
Kiba saw Y/n wasn't holding his spear but it was leaking a green aura
Y/n: Not bad trying a different approach instead of going head on
Mordred was training Issei and Akeno, she had Akeno perform her spells which she felt were strong but could be stronger, Issei was tasked with the instruction of boosting until he felt strong enough then create an energy orb that he had no idea to create
Mordred jumped back with her hands in her pockets to avoid another one of Akeno's strikes
Mordred: Not bad Akeno but it seems you can only shoot lightning in one direction
Akeno: You mean you want me to shoot it in another direction?
Mordred: Of course
Clarent materialises in Mordred's hand, she then raises it and it's covered in a red aura that shoots lightning out in every direction
Akeno: You can do that?
Mordred: Yeah... but I don't I find it useful, I'll teach you how to do it
Ddraig: {EXPLOSION!}
Mordred: Oh?
They turn to see Issei's boosted gear glowing
Issei: Alright here I go!
Sticking his hand out he closes his eyes to concentrate and for a second a red orb was seen before disappearing
Akeno: You think he can do it?
Mordred: Not now but if he keeps his concentration then maybe by the 5th day we'll be good
Issei falls to the ground panting, they then hear an explosion and turn to see a tree disappearing in a red light and Rias walks from the trees
Mordred: I see you listened to what I told you to. do
Rias: I've gotten a bit faster
Mordred: I see then let's focus on making your aim better too
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Day 5 (3rd Person Pov)
Everyone was in a clearing where Kiba, Issei and Y/n stood
Asia: Are you sure they'll be safe Mordred?
Mordred: Hell yeah... well I know my brother will as for Issei and Kiba, I can't guarantee it
Asia: But it's just a sparring match right?
Mordred: Yeah yeah, don't worry Asia
Issei: Tell us when your ready
Y/n: I'm ready
Kiba: No weapon?
Y/n stood with his arms crossed as he blinked at Kiba
Y/n: Nope
Issei: Your funeral!
Ddraig: {BOOST!}
Issei runs forward then throws a punch at where Y/n was to be met by air, he turned around to get kicked in the back making him fly back, Kiba then charged forward with a kendo stick with much more speed than he originally had and aimed to smack Y/n's head with it
Leaning back he avoided Kiba's strike then raised his left leg and kicked his chin making him stumble back, Y/n then jumped off his right leg and spun midair kicking Kiba's face with his left leg forcing him to fly back into the ground
Issei: I've got him this time!
Issei ran forward with his gear boosting once more, Y/n stared at him as Issei then punched his face
Issei: Ha! Yes! I punched him!
Issei looked to see Y/n wasn't even fazed by his punch
Y/n: Well done, you successfully landed a punch on someone who allowed you to punch them
Issei then felt his foot dig into his stomach making him crash into a tree behind him, Kiba then ran at Y/n and disappeared once he was in front of him, he then appeared behind him and tried to hit him with his kendo stick only to feel a fist punch him backwards
Mordred: God this is boring
The devils then held their heads in pain confusing Mordred
Mordred: Oh right you can't be hearing that word, sucks to be you
Issei: That's it I've had enough!
Issei got up and charged as he approached Y/n a red orb appeared where his gauntlet was he then placed it in front of him
Issei: DRAGON SHOT!
The entire wave engulfs Y/n as it travels back to a mountain blowing a hole in it, smoke then covered the entire place as the devils tried to look through it
Rias: Did Issei win?
Mordred: You honestly think an attack like that would do something?
The smoke clears to reveal Kiba with a broken Kendo stick but what shocked them more was Y/n with his arms crossed didn't even look scratched and still held the same bored expression on his face
Y/n: The energy was good in that attack, I'd say our training is working a bit but-
Y/n appears behind Issei
Y/n: You've got a long way to go to give me a challenge
With a quick chop to the neck Issei was knocked out, Y/n then places his hands behind his head and yawns
Y/n: *Yawning* Mordred you take over, I'm going to sleep
Asia: B-But you were going to teach me and Akeno how to use our magic better
Y/n looks at Asia who looks like she's about to cry then at Akeno who smiling at him very very innocently, more innocent than he'd like
Y/n: *Sighs* Fine come on
Asia: Yay!
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So we've seen Y/n and Mordred training Rias's peerage but will their training be enough to take down Riser, I guess we'll find out when it happens