Kingdom Key D

This alternate version of the Kingdom Key is called Darkside and, among fans, referred to as the Kingblade or the Inverse Kingdom Key. Darkside was found in the Realm of Darkness. Since Darkside is a reverse colorization of the Kingdom Key, it is believed that these two are the original Keyblades.

It wasn't the King's since before Kingdom Hearts. In fact, his original Keyblade was the Star Seeker, as shown with King Mickey wielding it in Birth By Sleep when he was still an apprentice of Master Yen Sid. 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. These three Keyblades are the only ones shown with Keychains.

It's unkown exactly how the King obtained Darkside. It is interesting to note that the Keyblade is very much an anti to Mickey's Light personality.

In Kingdom Hearts II, he is not shown wielding any weapon, except Darkside and his hilarious wits in Timeless River.

It was originally seen in the closing video for Kingdom Hearts. It is expected to appear in Kingdom Hearts coded.