(Birthright and Rainbow Ranger prepare to fight Dark Primordial and Ark Zero-One as suddenly one more dimensional gap opens up as Ethan, Aruto, Touma, Ikki, Ace and Hotarou show up.)

D. Primordial: I see you brought reinforcement, Primordial. You'll need it.

Ethan: Please, I can take you out by myself.

D. Primordial: Are you saying those five will be just deadweights?

Ethan: (laughs) Daijoubu deshoo. Datte kimi... yowai mo!

(Ethan smirks as he prepares to transform, and so do the five Reiwa Riders.)

JUMP!

BRAVE DRAGON!

REX!

SET!

HOPPER1! STEAMLINER!

AUTHORISE!

REKKA BATTOU!

COME ON! R-R-R-REX!

Riders: Henshin!

KAMEN RIDE: PRIMORDIAL!

PROGRISE! TO-BIA GA RISE! RISING HOPPER! A JUMP TO THE SKY TURNS TO A RIDER KICK!

BRAVE DRAGON!

BUDDY UP! OHING! SHOWING! ROLLING! GOING! KAMEN RIDER REVI! VICE! REVICE!

DUAL ON! GET READY FOR BOOST AND MAGNUM! READY, FIGHT!

GOTCHANKO! STEAMHOPPER!

(They transform into their Kamen Rider Forms.)

Primordial: I am the King of all Kamen Riders & DaiKaiju Heroes, and no one can stand against my powerful might. KAMEN RIDER PRIMORDIAL!

Zero-One: There are people who can stop you both... and that's us!

Saber: We shall decide this story's ending.

Revi: Let's go at once!

Geats: Now, here comes the highlight.

Gotchard: Gotcha!

(Then they charge at the duo, but as Birthright tries to attack Ark Zero-One, she punches one of his legs before clashing with Saber and overpowers him. Revi and Vice try their luck, but are easily outclassed by Ark Zero-One's attacks as she kicks Revi.)

Vice: Ikki!

(As Ark Zero-One is about to execute her finisher, some portals open up, revealing a group of Daikaiju and Megaforce Reiwa Heroes.)

Yuri Ikari/Kamen Rider Black Sun

Virgul the Black Sun Victorian Dragon Kaiju

Vernon Robertson/Vero-One the Victorian Dragon Knight

Haos Virgo the Light Victorian Dragonoid

Nathaniel Saturday/Ultraman Z

Karter Quinton/Ultraman Great

Toad Skywalker/Dino Fury Red Ranger

Nigel Tennyson/Galaxius

(Then the Daikaiju Heroes make their poses.)

Daikaiju Heroes: We are... the Reiwa Daikaiju Heroes!

(Next is the Megaforce Heroes.)

Megaforce Heroes: And we are... the Reiwa Megaforce Heroes!

(Meanwhile, Primordial and Dark Primordial are still fighting each other as they prepare to change forms.)

DAIKAIJU RIDE: VIRGO JUNIOR!

DARKAIJU RIDE: SPACE VIRGO!

(They transform and keep fighting as both Black Sun and Ultraman Z come in to back Primordial up.)

Primordial (Virgo Jr.): Nice to see you again, Yuri Ikari.

Black Sun: Same, Ethan Frederick.

Ultraman Z: Well, as you can see, Yuri and I joined forces ever since my parents Doc and Drew got rescued from that bastard Gendo Ikari.

Primordial (Virgo Jr.): Well then, let's finish this Dark Primordial guy.

Black Sun/Ultraman Z: Right!

D. Primordial (Space Virgo): (stern) Azu! I need back up here!

(Ark Zero-One joins Dark Primordial as both sides prepare to execute their finishers.)

FINAL ATTACK RIDE!

ARK RISING IMPACT!

Black Sun: RIDER KICK!

Ultraman Z: ZESTIUM BEAM!

V-V-V-VIRGO JUNIOR!

SP-SP-SP-SPACE VIRGO!

(Both sides collide their finishers as both Daikaiju and Megaforce Heroes nod in agreement and back the trio up. They perform their respective finishers as they help Primordial, Z and Black Sun to overpower Ark Zero-One and Dark Primordial. Azu reverts back and feels her body electrocuting.)

Azu: (angry) Don't think you won, humans! Ark-sama will still prevail!

(Azu then faints and explodes as Dark Primordial, who is reverted to his base form, glares at the heroes.)

D. Primordial: Curse you...

(Rainbow Ranger then prepares to change forms.)

Rainbow Ranger: Senki Change!

SHINKENGER!

(Rainbow Ranger becomes Shinken Red while Primordial prepares to transform as well.)

KAMEN RIDE: DECADE!

(Primordial becomes Decade, and then both perform their finishers.)

FINAL ATTACK RIDE: D-D-D-DECADE

Rainbow Ranger (Shinken Red): REKKA DAIZANTOU!

(Dark Primordial tries to counter, but gets overpowered by the combined forces of Primordial and Rainbow Ranger.)

D. Primordial: YOU'RE GOING TO PAY FOR THIIIIISSS!

(Dark Primordial explodes, and then the dimensional gap opens up again.)

Black Sun: Well, I guess it's time to go home.

Ultraman Z: Yep!

(They return to their respective universes as Birthright gets up.)

Birthright: Now only that bitch remains.

????: You have insulted your own mother for the last time!

(Everyone turns to see Kamen Rider Corona and her army of Coronaviroids as they get in their fighting stances. The final battle is about to begin.)