A/n pov

Within another universe a ominous cloud surrounded the Earth. 

???: He's come again to finish things... Kiba.

Kiba: Yeah I know I..I don't think we can beat such a monster

Issei.

Issei: We got no choice that bastard killed Rias everyone else. If we don't stop him now;their deaths will have been for nothing!

The Issei looked up seeing the fog forming down to Earth. With purple eyes forming in the clouds Kiba was left helpless when; he saw his arm was slashed off.

Kiba: AARRGGH! F-FUCK MY ARM!

Issei went to punch the  Monster in question only for it to block;leaving the  continent leveled in the process. As the shadows faded the sight of the  World breaker Y/n was seen. Without much effort  the Y/n  punched though Issei's armor;and reached for his heart. Hoisting him in the air the  Demonic Y/n scoffed.

Y/n(World Breaker): I thought this would give you a chance to pose a threat to my World Breakers; It seems I was wrong.

Issei;*Vomits blood* Y-You....

Gripping Issei's heart Y/n seemed to suck the power from the Dragon Emperor's body. When Issei's body was revealed the Y/n threw his body,tearing out his heart and sending his body to the moon. Issei's blood formed around the World Breaker before he crushed Issei's heart.

Y/n:(World Breaker): This is what absolute power is... I'll make this whole multiverse truly cleansed. 

Kiba: *coughs* Y-You sick  heartless demon...  M-Master Rias gave you e-everything a-and this is how you repaid her?

Y/n(World Breaker): You truly believe I am that same  naive fool? Hmph you truly are a pathetic however I supposed you can be useful for something,

Y/n reached his hand forward towards Kiba leaving only his screams to echo through the world.

(Back to the present)

The Reaper Y/n swung down at the World Breaker who responded by kicking him back. Cursing the boy formed small cero blasts before unleashing them in a rapid  assault.

Y/n(NOP): CERO METRALLETA! 

The World Breaker chuckled as he raised his hand out towards the attack.

Y/n(World Breaker): I see perhaps your worth using him after all.

Y/n(NOP) (Mind) What the hell is he planning?

Y/n(World Breaker) Omega Ddraig awaken.

The reaper watched in shock  as a dark crimson energy surrounded the World Breaker;revealing the twisted Sacred Gear.

Y/n(NOP): W-What the hell is that THING EVEN DDRAIG?!

Y/n(World Breaker): This is what he should have been. A being capable of letting anyone who possess him to DOMINATE. As you and your universe will found out.

(Meanwhile in the world of the living)

While the streets flooded with Hollows and Sinners Tatsuki was seen rushing through the streets.

Tatsuki:(mind) HOLY SHIT I-IT'S CHAOS! W-WHAT THE HELL IS HAPPENING?!

Tatsuki stopped when she saw a Soul Reaper had smashed into a wall covered in blood.

Tatsuki: H-HEY ARE YOU OK?! G-GET UP WILL YA WE NEED YOU SOUL  REAPERS TO HELP US!

Soul Reaper: S-Shit So...this is it? Dying here with only one girl to notice me?

Tatsuki: W-What come on ya can't die here, not like this!

???: TATSUKI HELP!!!

Tatsuki: O-OH NO THAT'S  AIKA AND THE OTHERS!

Soul Reaper: W-Wait w-what are you t-thinking human?! Y-You'll die if you go out there.

Tatsuki stopped then clenched her fist and gritted her teeth. 

Tatsuki: Yeah.. maybe your right. But i'm not gonna sit back while I know Y/n and the others are off somewhere;fighting for their lives. I'll fight even if I know it's a meaningless fight;some long as  someone I knew could have atleast a second longer of living!

Soul Reaper: T-Then in that case l-let me g-give you....a g-gift.

Tatsuki: Huh?

The Soul Reaper aimed his sword at her chest then smirked. 

Soul Reaper: W-With the last of my energy I-I'll give you everything I've got. J-Just let this sword go through your chest; And you'll become a Soul Reaper.

Tatsuki; I....alright then give me your blade! I'll do anything to help everyone!

Aika and the others cowered  as a Sinner went to hack them down;until Tatsuki bursted out of light. Hacking apart the sinner in of the girls Tatsuki stared down in shock at her new found power.

Tatsuki: So this is  what being a Soul Reaper is like? W-Woah this is insane!

Sinner 2: Who the fuck is this bitch?!

Sinner 3: Who cared gut her like the rest!

Tatsuki watched one of the sinner bolt towards her with their chain. Tatsuki sidestepped the Sinner's attack then kicked them in two. Punching  another  back Tatsuki jumped into the air after the rest.

Tatsuki:(Mind) Wow....this power everything is like it's in slow motion.

Compared to al the times I trained my body through karate;it's like i'm on a whole new level.

Tatsuki dodged another's slash then swung her sword;slicing them in two. Aika and the others stood in awe trying to process the battle going on before them.

Katase:(Mind) I can't believe that's the same Tatsuki we know. 

Murayama:(mind) Arisawa can win this can't she?

Tatsuki punched a hollow through the head then felt another beast bursting towards her.

Tatsuki: What the-?

Before the beast could hit her it was blocked by Micheal appearing in a suit armor. Slashing the beast back far away;The faction leaders stood before the beast.

Micheal: Tatsuki Arisawa ....  stand behind us now.

???: So your this world's version of the faction leaders eh?

Sirzechs: No...T-This can't be...how could they do something to you

GRAYFIA!!!

Azazel: This is what they've do to those from other worlds?

Grayfia(World Breaekr):  Why are you so surprised? Out of all  world's I was clearly to be picked against fools like you. The world Breakers know what hurts you all and what it takes to make you crack; Like Millicas's  skull.

Sirzechs; This is unforgivable... to use my own WIFE against me? To not only corrupt her but;to  also make her kill her own son;our son. Even if she's of another world I WILL NOT ALLOW THEM TO LEAVE THIS UNIVERSE WITH THEIR LIVES!!!!!!!

Sirzechs roared  forming a P.O.D blast in his hand.

Sirzechs: MICHEAL,AZAZEL, YASAKA LET'S MAKE THESE TRUE DEMONS PAY!!!

Grayfia(World Breaker): True demons?...If doing what is needed to be done is evil;then we are the very Satan you hold the fake title of.

Yasaka;  This battle will truly be a war.

??? pov

???:It appears we'l be needed.

???2: Yeah  you better not get in our way.

??? 3: Tch relax will ya we'll be good.

Timeskip brought to you by this

3rd person pov

https://youtu.be/2dmrr3DxUK4

Back within Hell Sona is seen forming a blast to send at a army of Sinners.

Sona: We won't give to anyone!

With Rias following up with her P.O.D the two wiped out the group with ease.

Rias:(NOP) Come on everyone we can handle this!

Gregori dashed towards  a giant Hollow then jumped at it with a P.O.D enhanced  punch. Tearing through it's head Gregori  jerked himself back in  the air with his wings. Noticing a Sinner  charging at him with a spear Gregori grabbed it by the tip.

Gregori: I ain't got time for a punk bastard like you;GET LOST!

 With the roar Gregori smashed the Sinner into the ground below. Kiba However was seen cutting down Hollows with Xenovia. Gasper freezing them in time gave the two knights what they needed to end each monster. Orihime saw a Sinner going after Asia before she quickly summoned a shield to protect her.

Orihime: SANTEN KESSHUN; I REJECT!

Sinner 4: WHAT?!

Orihime: TSUBAKI!

After Orihime  pierced through the Sinner's stomach they were stunned; Giving Uryu the chance he needed to end them.

Uryu: Orihime are you ok?

Orihime: Yes I'll be fine Ishida thank you! Are you ok too Asia?

Asia: Yes thank you Orihime!

Koneko was seen punching back a Sinner then she used her Sage powers against them.

Koneko: We're finally getting somewhere.

Xenovia: Their numbers seem to finally be dwindling a bit. 

Kiba; Yeah I know-What the hell?

When four beams of energy came crashing down infront of them, the Devils looked on at the counterparts that stood before them.

Kiba(World Breaker): This battle of yours is only just beginning.

Rias:(NOP) I should've known there would be one of me who'd stay for madness like the World Breakers cause.

Rias:(World Breaker): We only serve what our Master wants us to do.

Asia(NOP) B-BUT HOW COULD ANY OF US CHOSE TO DO SOMETHING  SO HORRIBLE!?

Asia(World Breaker) None of you would understand your too blinded by fake innocence.

Akeno and Sona fired at the World Breakers causing them to jump back.

Akeno(NOP): That's enough from you twisted fakes.

Akeno(World Breaker): *smirks* I agree we've wasted our words long enough.

Kiba and Xenovia rushed the World Breaker Kiba only for their strikes to be blocked.

Kiba(World Breaker): Lets's see how long you'll last.

(Meanwhile with Raynare)

Raynare  flew at Toguro with a powerful punch causing him to burst through the building.  While Forming Purple energy in her hand Toguro noticed his power fading.

Toguro:(Mind) W-WHAT FORM OF POWER IS THIS?!

Raynare: GENOCIDE  BREAK SHOT!

Firing the overwhelming Blast Raynare stood in the air above the dusted remains of Toguro.

Kali: Good job  my Daughter now let us continue on against the rest of these foolish beings.

Raynare: Yeah..Hmm?!

Raynare flew around until she noticed Kunou about to be attacked.

Raynare: HANG ON KUNOU I'M COMING!

Raynare flew down  then chopped a big Sinner down when suddenly 2 blast bashed into the the others behind them..

 Raynare: Who was that?

???: Looks like we got them.

??? 2:*smirks* Yeah if we manage to do this we'll get millions of point back home I know it.

Raynare: Who are you 2?

Noel: My name is Noel Niihashi.

Ninny: And i'm Ninny Spangcole we're witches from the Soul Society  West Branch.

Kunou: Huh did you just say Witches?

Raynare: The Soul Society West Branch?!

Ninny:That's right now let us give you a hand with our magic.

???: GGGRRRRRR

Noel;Hey  Ninny be careful this one has the energy of a Dragon.

Aside the beast stood the now sinner Aaroniero who laughed at them.

Aaroniero: I'd worry more about becoming our dinner,

(Back with Y/n)

The reaper was seen slashing in the sky;lighting it up a blast of Sparks. The Reaper unleashed  a barrage of Balas at the World Breaker,only for them to be slashed.

Y/n(World Breaker): All of this power you possess and you waste it. Protecting those  who wouldn't do the same.

Y/n(NOP) Shut it!  You don't know a damn thing about us! We're not power  hungry scum like you!

The reaper swung his blade at the evil Y/n causing him to block it with ease.

Y/n(World Breaker): I've seen more than you could ever believe.  trillions of universes and nearly  50 thousand had already fallen before my World Breakers ever even came. 

The World Breaker pushed Y/n back then tried to slash him. The heroic Y/n jumped back then used flashstep to try and hit the World Breaker with a Cero enhanced sword strike.

Y/n(World Breaker): You think your world is so different then how truly naive you are!

Gregori watching clenched his fist then punched through the other Y/n before him.

Gregori:(mind) You can't lose here not like this you hear.

(Back in the living world)

Sirzechs and the other Faction leaders were seen managing to leaving little injuries upon the World Breaker Grayfia.

Grayfia(World Breaker): *Smirks*  Is that all you can do? I'm gravely disappointed!

Yasaka: Are you ok Sirzechs?

Sirzechs; Yeah i'll be f-fine.

Azazel: You have to get your head in the game Sirzechs.

Micheal: We can't do this without your aid.

Sirzechs: I know it's just so hard to have to get into the mindset of hurting my own wife.

Tatsuki: LOOK OUT!

The faction leaders saw Grayfia firing a magic beam until they saw a blue flame stop it.

???: Well buddy for your sake I hope that beating gave you the heart to do it.

Micheal: Who are you?

???: Heh the name is

Bruno  Bangnyfe and I'm here from Reverse London to give you some help.  

To be continued