Kingdom Key D

The Kingdom Key D (キングダムチェーンD) is a Keyblade used by King Mickey. It is an alternate version of the Kingdom Key, and is a Keyblade of the Realm of Darkness. Some Square Enix merchandise has called it Darkside or Dark-side.

It did not always belong to the King. Before Kingdom Hearts, he previously wielded the Keyblade Star Seeker, as shown in Birth By Sleep, most likely when he was still an apprentice of Master Yen Sid. In addition, this Keyblade was shown in the secret ending of Kingdom Hearts II called The Gathering, along with Sora's Kingdom Key and Riku's Way to the Dawn. Notably, these three Keyblades, along with Master Xehanort's Keyblade, are the only ones in the movie shown with Keychains.

It was originally seen in the closing video for Kingdom Hearts, and has appeared much more often in Kingdom Hearts II. It is expected to appear in Kingdom Hearts coded.

In Kingdom Hearts II and in Kingdom Hearts II Final Mix, when Sora faces one of ten specific bosses and faints, you can play as King Mickey until Sora is revived by using either Healing Light or by King Mickey losing enough health, forcing him to use a potion on Sora and retreat. During this time you can use this Keyblade. Unfortunately, King Mickey and his Keyblade lack a finishing move, so you can't defeat a boss as him.

Trivia

 * In Sunset Horizons, Aqua takes this Keyblade.