Roxas

The youngest and newest member of the Organization, Roxas , the "Key of Destiny", was "born" when Sora briefly became a Heartless. However, due to a combination of Sora's short time as a Heartless and Kairi's heart serving in Sora's revival, Roxas has no memory of being Sora. He wields two Keyblades, and controls the element of light and the Samurai Nobodies. His name is an anagram of Sora with an x added.
Roxas in "Another Side, Another Story [deep dive]".
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Roxas in "Another Side, Another Story [deep dive]".
Roxas's first appearance was in the Special Secret Movie "Another side, Another story..." that is unlockable if the player accomplishes certain tasks in Kingdom Hearts; he was the first Organization member to be revealed. He later appeared in an additional video, "Another Side, Another Story [deep dive]", for Kingdom Hearts: Final Mix. When pre-release screenshots and video showed this character without an Organization cloak, he was featured prominently, emphasizing his importance to the future game's plot. In the absence of an official name, fan names included Glowing-Eyed Unknown and Dual-Wielding Unknown as he appears in "Another Side, Another Story [deep dive]" and Blond-Haired Kid or BHK when he was shown in his Twilight Town outfit. The Square Enix-given name in Kingdom Hearts α Ultimania ~Introduction of Kingdom Hearts II~ was Mysterious Boy .
He is voiced by Jesse McCartney in the English version of Kingdom Hearts II and Koki Uchiyama in the Japanese version.
Story
During his time in the Organization, he and Axel became best friends, but because Roxas had no prior memories of his life before and had many questions as to why he was chosen as a Keybearer, Roxas deserted to find answers the Organization was unable or unwilling to answer.
Riku, motivated by his desire to help Sora regain his memories and awaken, confronted Roxas in the World that Never Was. Roxas was victorious in the first encounter; after Riku took possession of the power of darkness, Roxas was defeated. Riku took him to DiZ who placed Roxas in a virtual Twilight Town created within Sora's memories without any memory of the Organization and with a fabricated identity to throw off his pursuers. But while Naminé restored Sora's memories as DiZ wished, Roxas is affected by seeing his other self's memories in dreams. As a result of DiZ's scheme, Roxas lived a normal life in a simulated Twilight Town until his past came back to haunt him when Axel infiltrated the simulated town to save him from DiZ.
Despite Axel's attempts to stop him and the reclamation of his memories as the thirteenth member of the Organization, Roxas merged with Sora at the beginning of the game as part of DiZ's plan to use a "complete" Sora to fight the rest of the Organization. Despite the fact that Roxas seemed to have been assimilated into Sora, he appeared two more times in The World That Never Was near the end of the game. The first was a confrontation with Sora that led to a one-on-one fight. The fight is never fully explained and is left open for interpretation. Roxas appears once again with Naminé as they both combine with their others before Kairi enters the corridor of darkness back to Destiny Islands. He and Naminé imply that they will not fade but live on within Sora and Kairi as both a part of them and as their own separate beings, as seen in the ending cinematic when they smile at each other through their other selves.