The Oathkeeper (約束のお守り Yakusoku no Omamori?, lit. "Oath's Charm") is a Keychain for Sora's Keyblade which appears in Kingdom Hearts, Kingdom Hearts Final Mix, Kingdom Hearts: Chain of Memories, Kingdom Hearts Re:Chain of Memories, Kingdom Hearts II, Kingdom Hearts II Final Mix, Kingdom Hearts 358/2 Days, and Kingdom Hearts Re:coded. It also appears as half of Roxas’s dual set of Keyblades alongside the Oblivion, and was transformed from his original Kingdom Key after he absorbed Xion. Fundamentally, the Oathkeeper is symbolic of Sora's memories of Kairi.
The Oathkeeper is formed when Sora uses Kairi's Wayfinder as a Keychain. After rescuing her from Hollow Bastion in Kingdom Hearts, Kairi gives him the charm for luck in the Secret Waterway in Traverse Town. When Sora enters Castle Oblivion in Kingdom Hearts: Chain of Memories, Naminé rewrites Sora's memories, replacing Kairi's Lucky Charm with what appears to be a trinket from herself.
After Sora defeats the Darkside at Destiny Islands and speaks with Naminé, she reveals the truth, and the illusion is dispelled. Although Sora continued to possess the Lucky Charm throughout Kingdom Hearts II, he is not able to use the Oathkeeper until he returns to Twilight Town and learns where Kairi had been taken. In Kingdom Hearts Re:coded, Data-Sora obtains the Oathkeeper Keychain after he fights a hooded boy and learns the truth behind the mysterious message that appears on Jiminy's first journal. In Kingdom Hearts III, Sora can obtain Oathkeeper after delivering the Proof of Promises to a Moogle Shop.
The Oathkeeper's 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". Its Keychain token is Kairi's Wayfinder, a star sewn together from Thalassa Shells.
In Castle Oblivion, it is replaced by Naminé's trinket until the illusion over Sora's Thalassa Charm breaks. When it is summoned by the user, Oathkeeper emerges in a bright, yellowish-white light.
This Keyblade's name may come from the promise Sora made to Kairi after she gives him her Lucky Charm and that he promised to return to her close to the end of the game. The Japanese name of the Keyblade may refer to the Lucky Charm itself and the promise Sora made after Kairi gave it to him.
The Oathkeeper has a decent reach and is well-balanced in Kingdom Hearts; Oathkeeper is a good substitute for the Lionheart, in case the player hasn't been able, or didn't want, to defeat Cloud and Leon in the Hades Cup.
In Kingdom Hearts II, its ability of Form Boost makes it much more useful for leveling Sora's Drive Forms, rather than for regular battle.
In Kingdom Hearts 358/2 Days, the Oathkeeper's combos are the exact same as the Two Become One Keyblade.
In Kingdom Hearts Re:coded, Oathkeeper's Clock abilities are the best defensive abilities among all the Keychains in the game.
Notes and references
- Famitsu Interview; Nomura: "The Keyblades the boy who knows Sora is holding are the Oathkeeper and Oblivion from the first game. The precious "Oathkeeper", which Sora received from Kairi. The jet-black Keyblade, symbolic of Riku. / The Oblivion, at first, was called Riku's Keyblade. The boy who has the Keyblades from Riku (darkness) and Kairi (light)......Who is he!?"