In Kingdom Hearts, Oathkeeper is the Keyblade associated with Kairi and her bond with Sora.
The weapon is tied to the good-luck charm Kairi gives Sora before the Destiny Islands disaster. After Sora returns the charm to her during the story, its symbolic connection is reflected in the Oathkeeper Keyblade. Its design includes the charm's distinctive star-shaped paopu fruit motif, making it one of the series' most recognizable weapons.
Oathkeeper is sometimes confused with Kingdom Key, the ordinary-looking Keyblade Sora first wields, or Oblivion, a darker Keyblade associated with memories of Riku and Sora's losses. Oathkeeper is also important mechanically: in later games, it commonly represents light, friendship, and Sora's memories of Kairi. In Kingdom Hearts II Final Mix, it is additionally connected to the game's secret ending and Sora's progression toward dual-wielding.