OmegaStellarSolare

Once upon a time, Rei fell from the sky into the land of Hisui after meeting Arceus, who told him to seek out all Pokémon.

After that moment, he met Professor Laventon who invited him to join the Galaxy Team Survey Corps of Jubilife Village as a way of obtaining food and shelter.

The Survey Corps also wished to fill out the Pokédex, and so, after proving himself worthy, Rei was admitted into their ranks.

While exploring Hisui, Rei learned that a mysterious lightning striking down from the same space-time rift they were fallen out was causing the Noble Pokémon around the region to go on wild frenzies and attack people.

As part of his duties, Rei was commanded by Galaxy Team Commander Kamado to seek out the recently frenzied Noble Pokémon.

Each of Noble Pokemon were overseen by a Warden belonging to one of Hisui region's two clans : the Diamond Clan led by Adaman, and the Pearl Clan led by Irida.

Each of these clans worships a deity they refer to as the "almighty Sinnoh".

But they disagreed upon the other clan's viewpoint whether this deity represented time or space.

During his travels, Rei also encountered with merchant named Volo from the Ginkgo Guild, who liked studying the history of Hisui.

Rei obtained many Plates after he quelled every Noble Pokemons' frenzy and befriended rideable Pokémons.

That was a good victory. Howerver, it was short lived.

The space-time rift in the sky suddenly expanded even further and the sky above Hisui turned red.

Suspecting that Rei, who fell out of the same rift, was somehow connected to this, Galaxy Team Commander Kamado banished him from Jubilife Village.

Rei seeked help from both clans, but they refuse to help in order to maintain neutrality with the Galaxy Team.

Then, he met Cogita and the merchant Volo, and with their guidance seeked out the lake guardians to obtain the Red Chain.

Even if the Chain failed to work as planned, Rei was still able to catch both Dialga and Palkia, one of which is caught with an Origin Ball crafted from the Red Chain, causing the rift to disappear.

That was the moment that both pokemon of time and space showed their Origin Forms.

With the appearance of both Dialga and Palkia, the Diamond and Pearl Clans realize neither of them was worshipping a false deity and set aside their differences.

But this story hasn't been ended.

Volo asked Rei to investigate the remaining Plates and collect the ones they don't own yet.

He traveled around Hisui and collected 17 Plates from various sources, most commonly receiving them from the Legendary Pokémon of Hisui, with Volo and Cogita's help.

Afterwards, this is where Rei met Volo for the last time, atop Mount Coronet, where it is revealed that Volo's consorting with Giratina was the cause of the rift.

Obsessed with meeting Arceus, he attacked Rei in an attempt to take all Plates for himself but he was defeated.

And then, the Legendary Pokemon of antimatter, Giratina appeared, revealing to be under Volo's orders.

Yet, Rei really defeated it. Even its own Origin Forme wasn't enough to conquer Rei. Therefore, Giratina left.

In the end, Volo gave Rei the final Plate, allowing Rei to obtain the Azure Flute that you already knew.

Volo is surprised by Arceus having chosen Rei instead of him and leaves in anger, swearing to one day, he will conquer Arceus and create a new world, even if it will take him centuries to do so.

Even so, that wasn't enough for every plates Rei obtained. So he caught every Pokemons in Hisui Region and even Legendary and Mythical Pokemons.

The last one was the Legendary Pokemon who's behind Landorus at this entire time. The last force of nature, Enamorus.

Enamorus was known as the Herald of Spring.

Once Rei has completed the Pokédex, he returned to the summit of Mount Coronet and plays the Azure Flute, revealing a glowing stairway that leads him to the Hall of Origin, where Arceus challenges him.

After the struggling fight, this was the moment Arceus was defeated for the first time.

Therfore, acknowledging Rei's bravery, Arceus granted Rei a fragment of itself.

Rei not only was the first person to obtain Arceus' fragment but the legendary item different from The Archetype : the Legend Plate.

This concluded the journey after Rei was the first person to complete the Pokedex.

Then, the whole Galaxy Team gathered to celebrate Rei's completion of the Pokédex.

And that ends the story with all miracle Rei did.