Spoilers from included and/or represented works abound. Please read this fiction carefully.
Year 2200, 13th Hierarchical City of Kagutsuchi. Team RWBY is running away.
In the monorail, they met some familiar participants and various strangers...
"Team RWBY?" Teddie recognized team RWBY.
"I remember many of you!" Ruby recognized the Investigation Team.
"We meet again!" Yu approached.
Everyone gathered around.
"We're the Hegemony Gods, emanating our laws using the Throne." The Hegemonies introduced themselves. "And there's Caim, the pact knight who cannot voice, and Nowe, the New Breed."
"Nice to meet you." Ren greeted team RWBY. "Who are you?"
"Ruby Rose, a huntress from the Remnant." Ruby introduced herself.
"The others are Weiss Schnee, Blake Belladonna and Yang Xiao Long." Hyde continued that.
"Yeah yeah, the Remnant as it's called... the Remnants of the old world." Nowe commented.
Caim simply nods.
"Looks like we have to explain everything we know so far." Mercurius proceeded.
The Hegemonies then explained everything known so far about Zero the girl, except her real name.
"We're late to the incident?" Yang is surprised. "We already dealt with Mistral and Atlas."
"I remember you when we first met, you looked like you recently begin to handle the hell out of Vale." Yosuke remembered.
"When you were still from Beacon Academy, huh?" Yu asked.
"You're taken from different time." Mercurius responded. "Don't ask that any further."
"We know Empress Zero's real name, but we didn't have the chance to reveal it." Marie told team RWBY.
"We got to this world thanks to Kanzakai Station from mine." Hyde explained how the group got there.
"We're summoned by Nekron." Weiss explained.
"Wait... The one who initiated the Blackest Night!?" Satanael is surprised. "The undead-"
"The Lord of the Unliving." Blake replied.
"We're dragged into other worlds for no reason this time around." Yang is disappointed. "What a shame. Breaking from Atlas, and-"
"Let's go find Ragna and others!" Hyde interrupted Yang.
"Wait!" A mysterious girl wearing a red jacket appeared.
"You looks like Nu-13..." Yu noticed the girl.
"Are you Nu-13?" Hyde asked.
"Nu-13? Oh, but is she..." Ruby realized something's different.
"You're!?" The girl recognized the Investigation Team, team RWBY, Hyde and Linne.
"It's a Murakumo unit, v-No. 13-, after all she has been through." Mercurius revealed.
"Precisely." Nu confirmed.
"Miss, where's the man, Ragna!?" Ruby asked Nu.
"Ragna is involved in a battle between Celestials and..." Nu explained.
"You mean Celestial and the other versions of this world's people fighting each other to kill the Super Sentai and Power Rangers!?" Hirume responded.
"How do you know!?"
"Super Sentai and Power Rangers were blackmailed, so they used their Megazords as a countermeasure." Ren explained. "I know about their recent actions."
"I'm surprised you know them that much." Nu is (indeed) surprised.
"It's complicated and dangerous." Mitra warned everyone.
Meanwhile, people from the world with the Azure, and the Celestials from various worlds, are all killing each other for to kill Super Sentai and the Power Rangers first.
"Die!" As everyone there is warring with each other. "We kill Super Sentai/Power Rangers first!"
There, the strongest of Mechas, Gattais and the Megazords are stepping on several of the soldiers there, crushing them to prevent them from getting in the cockpits.
And there's also the bloody Kisaragi: The familiar but now-paradoxical Ragna the Bloodedge, his brother Jin Kisaragi, and the odd-but-poor sister Saya Kisaragi (BlazBlue) (a.k.a. Noel Vermillion).
"Who the hell are you!?" Ragna have no idea of those Celestials.
"Tsk! It's all violence and fall!" Jin is frustrated. "These mechas send to be the only remotely trustworthy thing here..."
Beast X-King Ultrazord suddenly noticed the siblings.
"Why is mecha looking at us?" Saya is confused.
"Who're they!?" The Grid Battleforce Rangers doesn't know who those siblings are.
"Damn! Brothers, we're from an entirely different world than theirs!" Jin facepalmed.
"Well... it's Ragna=the=Bloodedge, Jin=Kisaragi and Saya=Kisaragi." Ragna introduced himself as well as Jin and Saya. "You can also call the latter as Noel=Vermillion."
"We're the Azure siblings." Saya introduced the siblings. "We're from the world of BlazBlue."
"BlazBlue!? That Azure shit?" Devon Daniels, the Grid Battleforce Red Ranger recognized BlazBlue.
"We need your help!" Ragna shouted. "This war is out of control!"
"Guys! We have Ragna the Bloodedge, Jin Kisaragi and Saya from BlazBlue in the battlefront!" Grid Battleforce Red reported.
"BlazBlue?" Hiromu Sakurada, the Red Buster of the Go-Busters (Tokumei Sentai Go-Buster) "These three people from the world of BlazBlue!?"
A Sideways Rift appeared besides the siblings, with the Hegemonies, the Investigation Team, team RWBY, Hyde, Linne, Nowe, Caim and Nu all emerging from it.
"Oh my, mister!" Ruby recognized Ragna.
"I'm back, pact!" Nu approached Ragna.
"Ragna! Jin! Noel!" The Investigation Team, the rest of team RWBY, Hyde and Linne approached the siblings.
"It's you! I thought I can never meet you again!" Ragna is surprised. Nu hugged Ragna right away.
"Yes, finally!" Hyde is excited.
"Kiddo, you're back too!" Ragna is even more surprised.
"Nice that you're all back." Yu commented.
"And we're here to help." Marie told everyone. "Let's go somewhere else. It's too bloody here."
"Good luck, all!" The Sentais and the Rangers shouted.
Marie and her Hegemony followers (Mercurius, Ren and Reinhard) connected themselves and teleported everyone away.
Back to Phantom Field...
"The Hegemonies are the Hegemony Gods, able to emanate their own laws using the Throne, across the universes." Mitra explained who the Hegemonies is.
"Compared to the Transcendent-types, who internalizes their own laws and ignores the Hegemony Gods' own laws." Hirume explained the Transcendent-types' powers.
"My brother possesses the Blue Grimoire, aka the Azure one." Jin explained the powers. "I have an ice sword, but my sister I used to bully, well... it's complicated."
"Listen." Then the Azure siblings explained their stories: how they came to be, their actions, and all that entailed till the end of the journey, etc.
"Stories long as fuck." Hajun is confused. "And the end of 22nd century and then begin year 2200?"
"Duh." Jin Kisaragi.
"Jin only hated my sister because she stole attention. Then it ended up complicating because of some evil people. And it snowballed from there." Ragna concluded. "Those stories also involved time loops as well."
"It's our turn." Then the Investigation Team explained what happened in Yasoinaba and their investigation of that, from late 2011, as well as their fighting tenures in May 2012.
"Done with the backstory, guys." Ren stopped everyone. "We're here to investigate."
"About System No. XX?" Ragna asked.
"Exactly." Yomi confirmed.
"That System was created in our world." Ragna replied. "She uses Keystones to choose whichever worlds would she use."
"We have been in that tournament, so we know it quite a lot." Yu noted.
"Yeah, me, Linne and some In-Births has participated as well." Hyde noted.
"It was awesome to see that big sword-scythe!" Ruby commented. "By the way, why it's worn out, cracked, and tired with... a vampire?"
"That Rabbit..." Ragna realized it's from Rachel Alucard. "She's trying to find me since after my sacrifice?"
Shadow Yu then appeared out of nowhere.
"Oh no, not the fake Shadow again..." Yu noticed the Shadow. "Persona!" *summons Izanagi*
"These are Shadows, like this one." Jin stood up and took with his sword, Ice Sword: Yukianesa.
"Heh, Shadows like these were basically about the dark side of a potential Persona user, apparently." Yosuke stood up.
Yu, Yosuke and Jin approached Shadow Yu. The latter then summoned the ring, trapping them all there.
"Good luck, you bastards!" Ragna shouted.
"Brother, good luck!" Saya cheered.
"You can do this, Sensei!" Teddie cheered.
"Persona!" Yosuke summoned his Persona, Jiraiya.
A portal appeared beside Shadow Yu.
"Huh? A portal?" Jin is confused.
"It's you, the fighters from the wrong worlds." It was the Mad Titan, Thanos.
"Who are you!?" Everyone except Shadow Yu and the Hegemonies is surprised.
"It's Thanos. Who once decimated half of the life in his universe." Magsarion responded. "The Mad Titan."
"You guessed it correctly." Thanos confirmed.
"Bring on the Ring!" Shadow Yu then went to combat.
"Fight us." Thanos is ready.
"Ugh!!! If someone manipulated the Mad Titan..." Reinhard is frustrated. "Who would be?"
"Let's find the others!" Yomi suggested.
"No, we can't leave until the fight is won!" Rise warned Yomi.
"Okay then..." Yomi relented. "Let them fight."
"We're ready!" Yu, Yosuke and Jin them straight out attacked.
Thanos brute-forced to try and overpower, but Jin used Yukianesa to freeze him. Yu and Yosuke traded blows against Shadow Yu. Thanos struggled and pushed Yu off, but Yosuke counterattacked. Jin froze Shadow Yu, and the fight involved the two teams trading blows to each other.
"Mad Titan, it's enough!" Yu went for Zio skill, electrocuting Thanos.
Jin stabbed Shadow Yu.
"Ugh!" Shadow Yu shouted.
"Astral, out!" Jin then Astral heats Shadow Yu, finishing them off.
"K.O.!" The announcer exclaimed.
Shadow Yu fell down, dissolving into Shadows.
"GG, strangers." Thanos respected everyone. "I'm here to test you with these Shadows."
The ring disappeared, freeing everyone.
"We won!" Yosuke cheered.
"I know where the System No. XX is." Thanos told everyone. "I was summoned by that machine."
"Oh really?" Marie is glad.
"Follow me." Thanos decided to choose the way.
The location is originally Cross Field, but filled with ruins of Dusty Depot and its versions, ruins of Greasy Grove, the remains of Bionis and Mechonis, traces of crystals everywhere in the landscape, the Last Reality's Pyramid coated with Chrome in the middle of the entire landscape, and corpses and blood everywhere from all the deceased realities. The sky's taken from the World of Light.
"What's this place?" Sophia, an AI arrived at the scene.
"It is a wasteland." Zenkichi Hasegawa, the Wolf of the Phantom Thieves of Hearts, arrived in the scene.
"So this is..." Ren Amamiya, the Joker, looked around the scene.
Cross-trivia: ThePhantom Thieves of Hearts, also known simply as thePhantom Thieves, are a group ofPersona Usersin thePersona 5 (and its other). Sick of the deception, hypocrisy and corruption around them, the Phantom Thieves are devoted to "stealing" the corrupt hearts of evil adults in order to change and reform society for the better.
"Joker, this is the Cross Field previously rumored to have been." Morgana revealed. "However..."
Ryuji Sakamoto (Skull) then crashed the nearly rubble to check the environment.
"There's traces of the another worlds lying around." Ann Takamaki (Panther) observed.
"Fox, Queen, and Noir, do any of these look familiar to the rumors?" Morgan asked Yusuke Kitagawa (Fox), Makoto Niijima (Queen) and Haru Okumura (Noir).
"Not really." Yusuke replied. "This barely resemble the Cross Field of those rumors at all."
"Wastes and ruins from another worlds..." Makoto observed. "Sounds like some rifts ended up messing this place."
"I've done scanning the scene and atmosphere." Futaba Sakura (Oracle) reported. "This is indeed the rumored Cross Field, but it's littered by the ruins of several other worlds."
Kasumi... um... Sumire Yoshizawa (Violet) noticed a massive flying battleship behind the Phantom Thieves.
"Are these... from another worlds as well?" Sumire asked.
The Phantom Thieves looked behind, and is shocked by its sheer size and dominance.
"What!?" The Phantom Thieves is shocked.
The ship landed nearby, and some mechas flew out. Turns out it's Shin Halberd.
"Shin Halberd. Someone finally fixed that." Ren Amamiya recognized it.
"Joker, are you serious!?" Morgan is shocked.
"Because I was a part of the Smash." Ren Amamiya referred to his (playable) appearance in Super Smash Bros. Ultimate. "Whose fighters currently works for some alliances."
"Huh. That explains why you occasionally showed off that invite." Goro Akechi (Crow) remembered.
"Crow, you know." Ren Amamiya explained.
Gunleon, Virgora Glory, Shurouga, Van Ein, Huckebein 30th, Grungust, Aussenseiter, two Gun-Arks, Ixblau, Alpheart and Nineball Seraph landed.
"You're the Phantom Thieves of Hearts?" Tak asked.
"Mister Kepford?" Ren Amamiya recognized Tak.
"Yeah, and you have all the members?" Barrel asked.
"Spot on!" Sophia (aka Sophie) exclaimed. "By the way, we only heard you for the rumors."
"Those rumors about us is related to Empress Zero." Rand responded. "We're trying to figure it out what's going on exactly."
"Fortunately, we are doing the same too." Morgana agreed.
"Then we're on the same side." Autumn-Four replied. "Anyways, I'm Autumn-Four. My otherworldly companions are Tak, Marina, Barrel and Fei."
"Masaki Andoh. Cybuster!" Masaki introduced himself.
"Sanger Zonvolt here." Sanger greeted the Phantom Thieves. "Elzam is my partner. There's also Sainklaus as well."
"I kinda know you all from the rumors already, but thanks." Futaba told the mecha pilots.
"Shin Halberd is landing." Schatte told everyone. "Make the way!"
"Ok!" Rand, Honoka, Setsuko, Asakim, Elzam and Az agreed.
"You'll meet the alliances soon." Edge told the Phantom Thieves.
"Nineball Seraph... Who's it pilot right now?" Ren Amamiya wondered.
Not long after, Shin Halberd landed. Dragonturtle MK. II also landed as well.
"Oh, the Phantom Thieves of Hearts!" David greeted the Phantom Thieves.
"Oh, cyberpunk! What's your heart?" Sophia meets David.
"Nice to see your around, Joker." Reiji welcomed Ren Amamiya.
"This is the Cross Field." Superman observed. "But it's littered with Dusty Depot, Bionis, Mechonis, crystals, and dead people's flesh and skulls from all the worlds that's destroyed so far."
"Toon Squad comes in service!" LeBron saluted.
"Mickey Mouse and Bugs Bunny, say hi to the Phantom Thieves!" Saint Advent bright Mickey Mouse and Bugs Bunny.
"Wow! You came back to reform yourself!?" Asakim is surprised.
"What!?" Az is shocked.
Then, a group is running towards the Phantom Thieves.
"It's the Phantom Thieves!" Turns out, the Investigation Team is alongside team RWBY, the Azure siblings, v-'No-13', the Hegemonies, Hyde, Linne, Nowe and Caim.
"Wait... You're the Investigation Team we met in that cinema!" Morgan as the Phantom Thieves recognized the Investigation Team.
"Isn't that... the Hegemonies!?" David is surprised. "It's me, David Martinez from Santo!"