A Hero doesn't keep up.... They keep and protecting innocent live from them....

Seeing of Snipe shooting at robot, changes to Daizo giving electricity on grunts, Rogue knee on the robot.

They believe to fight in justice and freedom.

Seeing of Shinobi slashes on his enemy, GekiViolet throw the punch at them, Abyss slashes them with his sword.

I know I can be one....

....

???: Tsubasa!

Making the young man name Tsubasa Kudo, as he released the heavy breath before he woke up. He rushes quickly to the class.

Person: Tsubasa Kudo, the adoptive son of Doggie Cruger, the Commander of Special Heroes Force. He has trains in excellently, sometimes to be clumsy enough for that.

Seeing of Tsubasa's personal life.

Person: Alongside with his classmate and roommate, Pyra Flare the new cadet of the S.H.F Academy.

Seeing of Pyra helping him, changes of her friendly and kind smiles.

....

Until then..... The Mission Went Wrong....

Seeing of Shocker Commander saying farewell to S.H.F, changes to Parademons started charging and attacking to killing the S.H.F Agents.

Seeing of Doggie pushed Tsubasa and Pyra away going and enter through of the portal, seeing of his adoptive father.

Tsubasa: DADDDDDDDDDDDDDDDDDDDDDD!!!!

Doggie: Be strong, Tsubasa.... Be strong.... *Sad smiles*

....

And now....

Seeing of Tsubasa and Pyra still in their Battle armor uniform to wandering and checking around the city.

Pyra: Where are we?

Tsubasa: This is....

Looking at the TV news of All Might, making them looks surprised.

Pyra/Tsubasa: MY HERO ACADEMIA?!?!? *Shock tone*

....

Seeing of Tsubasa and Pyra adapting the role in the world to meeting of the new friends, like Izuku Midoriya, Kiana Kaslana, John Doe, Kasumi Toyama and Nozomi Kaminashi.

....

But.... There is the new threats is coming...

Seeing of the citizens started to running away when the Neo Shocker army started to terrorize the city.

Shocker Commander: Soon... This world will be our... *cold tone*

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But... 

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There only person can stop them.....

....

Seeing of Tsubasa bravely standing there with the determine looks and holding of Neo Decade Driver.

Tsubasa: There only one who can stop you..... Is me! *determine tone* Henshin!

Kamen Ride: Decade!

Tsubasa transformed as Kamen rider Decade!

....

The Savior of World, the 10th Heisei Rider is here!!!

Decade slash against Tomura Shiragaki as he scream in pain, Dabi fire the blue flame blast at Decade as he dodge it and scene change to Decade shoot at Overhaul as he block it.

Scene change Decade shoot Pysga as he was flying, show Decade change into D-Faiz as he slash at Orga and Siren from World Of Faiz X Azur Lane.

....

A New Enemy!

Showing Shocker Commander, Herrscher Of Sentience, General Zod, Tomura, Dabi, All For One, Overhaul and Darth Maul.

....

A New Allied!

Seeing of Diend, Gokai Silver, Superman changes to team Kamen rider Decade standing there determine.

....

Seeing of Decade driving in his bike, changes to Decade swinging slashes against on his enemy is Dark Decade before they charged and clashed against each other.

....

Decade: Just pasting through Kamen rider, remember that!

My Hero Academia: The Savior of World!

Kaminari: Guys.... What the hell is that?! *fear tone and point*

Making them turns toward before open wide with the shock looks and feeling the fear inside of them.

Revealing the giantatic creature is to be larger then All Might, Endeavour and revealing it.....

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Doomsday!

Doomsday: 

https://youtu.be/FEW5a7ebxvQ

End Of Trailer

So what do you think? I add Doomsday as enemy to Decade and also General Zod & Darkseid as enemy to Decade. Also thank you for the idea, Doctmar123. I hope you enjoy this trailer, see you next time!