The χ-blade is the legendary Keyblade that is the counterpart to Kingdom Hearts. When Kingdom Hearts was lost in the deepest of darkness, the χ-blade was shattered into 20 pieces. 7 of light, and 13 of darkness. Tales tell of a Keyblade War, where countless Keyblade wielders created their own Keyblades to the image of the χ-blade. They fought each other and desired to take the χ-blade and Kingdom Hearts. Master Xehanort's goal is to aquire the χ-blade and start another Keyblade War. He first attempted to create it by having a heart of pure light (Ventus) and a heart of pure darkness (Vanitas) clash together. Vanitas managed to fuse with Ventus, and the χ-blade was created. During a metaphysical battle, the χ-blade was still incomplete and Vanitas attempted to complete the fusion within their combined hearts, but Ventus sacrificed himself to stop Vanitas. During a physical battle against Ventus-Vanitas, Aqua and King Mickey managed to destroy the χ-blade, 'causing it to explode.
- In the Jeffrey, Jaden, Hiccup & Friends' Storm Adventures series, the χ-blade was broken into 11 pieces of light. Not 7. And Xion is required for its completion.
- In Jeffrey, Jaden & Friends' Storm Adventures of Kingdom Hearts: Dream Drop Distance, it is revealed that the actions of Ansem and Xemnas were to restore the χ-blade. But Master Xehanort attempted again to recreate it by having his younger self bring 12 incarnations of himself into a gathering and form a second Organization XIII. He attempted to make Sora be the 13th Vessel, but this was thwarted by Jaden, Jeffrey, Lea, Riku, King Mickey, Xion, Donald, Goofy, and Jesse.
- In the Thunderbolts Adventure Series, the X-blade is the weapon that gave Courtney her scar under her left ear when she was a young pup.
- In the Twilight's Adventures Series, Twilight and the Rainbooms attempts to stop Anubis and the Heylin Empire from using their magic and 13 vessels of creating the X-blade.