Arcadia Movement
The Arcadia Movement (アルカディアムーブメント) is an organization of Psychic Duelists. They oppose Yliaster in respect of resurrecting the Crimson Dragon.
Sayer is the founder and former leader of the organization. He planned to find as many Psychic duelists as he could to use as soldiers and overthrow Goodwin. To achieve this goal Sayer was willing to do anything, even being ruthless enough to kill or torture (as evidenced by Toby Tredwell and Leo, respectively) to do this. They depended on Akiza's success in the Fortune Cup so as to let the world know of their ideals, even if that means revealing themselves to the rest of the people. When Akiza lost, they were back to square one since no one would join them. Lazar describes them as "a utopia for psychic duelists and fragile monsters that have been organizing actions and rallies in secret".
Sayer wants Luna to join the organization because of her power as a Signer and her power to go to the Duel monsters world. He reveals that the Arcadia Movement's goal is to assemble an army of duelists with unnatural powers to wage war against Goodwin and New Domino City in revenge for their discrimination. Sayer is clearly set out to use Akiza and Luna until this goal is realized. The organization also kidnaps children and trains them to be Psychic duelists, one of them presumed to be Misty Tredwell's brother.
After losing to Carly Carmine, it's unknown if Sayer is still alive, nor is it made known if any other members survived the attack either due to the destruction of their headquarters caused by Carly's Earthbound Immortal, Aslla Piscu, or those who were sacrificed to summon Misty's own Nazca God as well. However, Sayer did tell the other members to leave the building prior to his duel with Carly, but whether or not they were swallowed by Earthbound Immortal, Ccarayhua, remains to be seen.
As of episode 60, it turns out Sayer had indeed survived. He travels to Satellite to find Akiza once again. He finds Mina and Yusei instead, and pretends to be an agent sent by Goodwin. Sayer tricks and traps them in an underground cage, where he leaves then to drown in the flooding room. Sayer then leaves, and eventually finds Akiza already battling against Misty. He whispered a few certain words in her ear, and releases the Black Rose Witch inside of her to get revenge on Misty. However, in episode 61 Misty who has learned that Sayer was the one responsible for killing her brother, then orders her Earthbound Immortal to devour Sayer, thus killing him. However it was revealed in the Yugioh 5D's 10th Anniversary book that Sayer was Resurrected after Ccarayhua was defeated by Akiza and was taken to Jail by Sector Security.
Non-Canon
In Yu-Gi-Oh! 5D's World Championship 2010: Reverse of Arcadia, the player is a member of the movement during beginning of the game. It is later destroyed after the awakening of the Earthbound Immortals.
