
Sora is the main character of the Kingdom Hearts series. He is playable in Kingdom Hearts, Kingdom Hearts Chain of Memories, Kingdom Hearts II, Kingdom Hearts Dream Drop Distance, and Kingdom Hearts III. Although in Kingdom Hearts 358/2 Days, he’s playable only after unlocking him in Mission Mode and in Kingdom Hearts Coded, a virtual version of him is the protagonist.
Before Birth by Sleep
After Ventus’s heart is damaged by the creation of Vanitas, Master Xehanort brings the unconscious Ventus to the Destiny Islands. Here, Sora’s newly born heart encounters Ven in his Dive to the Heart. He offers to join hearts with Ven to prevent his heart from deteriorating any further until Ven’s heart can heal on its own. This connection mends Ven’s damaged Station, and as a side effect, it causes Vanitas’s face to resemble Sora’s.
Birth By Sleep

When Sora is four years old, he encounters Terra and Aqua, two Keyblade wielders, on separate occasions. He never speaks with Terra, but they see each other from a distance. Terra shows no interest in Sora because he is unable to sense his potential, and is instead drawn to Riku. When Aqua meets Sora and Riku, she senses that their friendship parallels that of Ventus and Terra, and she tells Sora to protect Riku if he ever falls into darkness. Sora, despite his confusion, agrees.

Later on, Sora and Riku rest on a beach. When they prepare to go home, Sora suddenly feels sad due to having sensed Ventus’s pain from their previous encounter. Riku tells him that maybe someone in another world is in pain and encourages him to reach out with his heart. Sora successfully calls to Ventus, whose heart has been lost after the destruction of Vanitas and the χ-blade. Ven’s heart makes its way to Sora’s Station in the Dive to the Heart, and Ven asks if it can stay with Sora while he sleeps. Sora, wanting to make Ven better, happily accepts, and Ven’s heart merges with him.