Eterna City

Eterna City is a city in the Sinnoh region. It's the city that Giratina picked long ago to hold Kowamote, the Dark Plate. The Mokusetsu previously visited this city in search of the Plate.

Two statues of Dialga and Palkia reside in this city. It's a landmark and was here for decades.

History
In ancient times when Arceus removed Manipulation from the world after growing displeased with the way it was being used, Arceus hid all the history books about Manipulation. These books were co-written by Arceus and Giratina, back when they were still friends. Arceus had the books hidden in Eterna City.

After Arceus was captured by the Tekiyoku, it was forced to reveal a way for them to gain ultimate power, particularly a way to have more power than Legendaries and Mythicals. Arceus told them about the existence of Manipuation so that they would spare its life. Arceus even told them where the books were hidden. Some Tekiyoku members then traveled to Eterna City to bring the books back to the headquarters. Upon examining the books, they believed Arceus about Manipulation. This led to Manipulation returning in modern times.

Plate
In ancient times when Arceus created its special move, "Omnipotent Purēto Scatter", it had Giratina pick out several cities and towns around the world to hide all 17 Plates. Eterna City was one of these locations. The Plate that was hidden here was Kowamote, the Dark Plate.

Present
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 *  SPOILERS MAY BE PRESENT IN THIS SECTION 

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The Mokusetsu first arrived in Eterna City in Episode 26. People traveling were Alain, Ash, Dawn, Zoey, Barry, Kenny, and Ursula. Immediately, Alain had Barry meditate to become an Electric Manipluator. It was successful.

They then walked towards the area where Alain's Plate-tracking move said the Dark Plate, Kowamote, should be. Enemies were close by and approaching. One showed himself next; it was Kagetomo. Zoey, Barry, and Kenny were surprised to see him, since they heard about how we vandalized Kasai Village back when they visited the place to help clean up from the damage. Another shock shortly followed when he brought out the other person with him, Heidayu. Heidayu revealed that after fleeing Kasai Village, he had joined the Tekiyoku. Alain and Zoey fought Kagetomo, while Ash and Ursula fought Heidayu. Dawn and Pikachu hid while Barry and Kenny worked to keep away nearby crowds.

During the fight in Eterna City, Ash suddenly gets stabbed from behind and falls. It was revealed to be Pierce, another enemy who's a Ghost Manipulator, making it impossible for Alain to be able to sense him. Ash was brought to the side close to a crying Dawn. Alain then fights Kagetomo alone, while Ursula fights Heidayu and Zoey fights Pierce. They're successful and make the enemy retreat. Zoey immediately rushes to heal Ash. Barry's previous inner voice comes back, declaring its determination to make sure Barry becomes a Dark Manipulator.

In Episode 27, with the fight over and Ash healed, the Mokusetsu searches for the Dark Plate. The area for it happens to be close to two statues; one is of Dialga and the other is of Palkia. Dawn expresses her concern about Ash's safety and worries about if he should really become a Manipulator. Ash insists that he should.

While searching, Barry finally admits to Alain his thoughts about becoming a Dark Manipulator. Alain exclaims that it's impossible in modern times, especially since Barry is already an Electric Manipulator. Barry mentions the inner voice he's been hearing, which Alain replies to by saying it's Barry's conscience, which is somehow corrupt. Dawn approaches Barry and offers positive advice while saying Barry doesn't need to turn evil to bring Paul home. These words deeply calm Barry down. Suddenly, the Dark Plate appears in Dawn's hands. Dawn says she planned to rid the darkness out of Barry just then when seeing him struggle and figured the Dark Plate would appear if she did. Everyone is happy that she found the Plate.

Later that afternoon, the group walks around Eterna City. Ursula leaves the group in order to continue her visit with her family in Snowpoint City, but expresses her desire to fully join the Mokusetsu later to fight in the final war. Before leaving, she whispers to Dawn that she'll be letting Misty and Iris know that she found Dawn. She says things will get worse if Dawn doesn't pay them money to help them with the Tekiyoku taxes.

Right after this, Alain tells Ash to begin the meditation for becoming an Electric Manipulator. Dawn, clearly uneasy, expressed a deep worry to Ash before this starts. Ash assures her that he'll be fine. During the meditation, he has a flashback to Dawn worrying so much for him and ponders things. Alain suddenly yanks Ash up from the meditation triangle and yells at him for not focusing on Ikazuchi. He stopped the meditation before Ash died from not concentrating. Alain says they'll try again after getting the third Plate in Sinnoh.

While remaining in Eterna City, Alain continues training Barry's Electric Manipulation and Ash talks with Dawn more. Training and preparation continue for several days and then they go to their next destination, Floaroma Town, to look for the Psychic Plate, Fushigi.

Characters From Here

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Trivia

 * Eterna City is simply named after the word, "eternal", perhaps a reference to how old and historical the city is in the official Pokémon games.
 * Eterna City was picked as the place where Arceus hid the Manipulation history books due to how ancient and historical the city is described in the games.
 * The statues of Dialga and Palkia are a reference to the fact that there are really statues of those two Pokémon in Eterna City in both the Pokémon games and the anime.