(Henry Tennyson is seen in the Tennyson Mansion as he suddenly sees Class 1-A.)

Henry: Union never learns, huh?

(Henry then prepares to transform.)

Henry: Henshin!

TURN UP!

(Henry becomes Kamen Rider Ancient Blade and charges at Class 1-A.)

Iida: There he is!

(Before Class 1-A could strike, Arnold comes in and prepares to transform as well.)

Arnold: Henshin!

OPEN UP!

(Arnold becomes Kamen Rider Ancient Leangle. Suddenly Stormfront comes in.)

Stormfront: Fear not, Class 1-A. I'm here to back you up and make them pay for destroying the Schnee Dust Company.

Izuku: I could care less about that company. All I care about is... AVENGING ALL MIGHT!

A. Leangle: Tch, please. You can't even avenge your mother!

Izuku: HOW DARE YOU SPEAK OF MY MOTHER?

(Out of a sudden, someone slit Bakugo's throat before punching through Izuku's chest, making the latter cough blood.)

Ochako: (worried) Deku-kun!

(The attacker is revealed to be Kirigami Hajime, who then turns to Ancient Blade and Ancient Leangle, giving them a death glare.)

Hajime: Henry Tennyson, Arnold Dark. You dare to use the power of the Undead! Today, I will destroy you and erase this universe.

(Hajime prepares to transform as well.)

Hajime: Henshin!

CHANGE!

(Hajime becomes Kamen Rider Chalice.)

Shoto: (stern) Another Kamen Rider?

(Chalice ignores Shoto and charges at both Ancient Blade and Ancient Leangle, who dodge his attack as they clash with him. None of the sides seems to be at advantage, but as they try a combined attack, Chalice quickly dodges and prepares for a quick finish.)

FLOAT! DRILL! TORNADO!

(Chalice then charges at the two Anciend Riders once again.)

SPINNING DANCE!

(Chalice hits Ancient Leangle with a spinning kick as Arnold is reverted back to normal.)

Chalice: (approaches Arnold) I'm taking your power away now!

(Chalice takes Arnold's driver, and then has a clash with Ancient Blade as both slash each other, but Chalice kicks Ancient Blade in the gut before slashing him. They slash each other again as Ancient Blade tries to land another one, but Chalice dodges the attack and executes the same finisher he used on Ancient Leangle.)

FLOAT! DRILL! TORNADO! SPINNING DANCE!

(Chalice finished Ancient Blade, reverting him back to Henry Tennyson, and then he takes his power away as well.)

Chalice: This fight is being broadcast around the entire world.

(Meanwhile at Union CIty, everyone is seen watching Chalice's easy victory over Ancient Blade and Ancient Leangle as he makes an announcement.)

Chalice: People of Union CIty... no, people around the world. This message is for you! The Apocalypse will start in two weeks. I'll give you a challenge. Both powerless and powerful people alike, you must find the real Monolith Slab and destroy it. If you can destroy it, the apocalypse will be stopped, and the world as you know will still live.

(Both citizens, true heroes, and even fake heroes are frightened by Chalice's declaration. Unbeknownst to them, a trio of heroes from another world are also watching the announcement.)

Gabriel: So Chalice is planning to destroy this world, huh?

Shiro: And making things worse, the Tennysons are in danger.

Hailey: What should we do?

Gabriel: (smirks) What we always do, saving this world.

Shiro: (smirks) All right, let's go and save the Tennysons from those fake heroes!

Hailey: Well, Deku deserves to die anyway! (calls Kiva-La) Kiva-La!

Kiva-La: (comes in) Here we go!

(The trio prepares to transform.)

G/S/H: (unison) Henshin!

KAMEN RIDE: D-D-D-DECADE!

(The trio become Kamen Riders Ancient Decade, Ancient Kuuga and Ancient Kivala.)

A. Decade/A. Kuuga/A. Kivala: Let's help the Tennysons.

(They go to help the Tennysons as the screen fades out.)

A/N: Gabriel and Hailey Hikari are AlstonChanAlstonChan's OCs while Shiro Serizawa belongs to KaijuMaster20