The Oathkeeper is gained by speaking to Kairi in the Secret Waterway in Traverse Town, after her rescue in Kingdom Hearts.The Oathkeeper reappears in Kingdom Hearts II. The Oathkeeper is one of the two Keyblades Roxas uses, the other being the Oblivion. The first time Roxas is seen using Oathkeeper (Another Side, Another Story), it appears more metallic than Sora's. However this is only an effect applied during the High Quality cutscene. The Keychain motif is of Kairi's Lucky Charm; a Paopu fruit-like star made of thalassa-shells. Its shaft displays two hearts, and its handle bears two angel wings, contrasting the bat wings that comprise Oblivion's handle. The teeth are fashioned in the shape of the Kanji for "light" (光), corresponding to the Oblivion's Kanji for "darkness". It can be seen as a Keyblade of light, to balance out Oblivion's darkness.
In Kingdom Hearts: Chain of Memories, the OOathkeeper card is obtained after completing Destiny Islands on the 12th floor.