The Circle of Life (サークルオブライフ Sākuru obu Raifu?) Keyblade is from Kingdom Hearts II and Kingdom Hearts II Final Mix. In a way, it almost replaces the Jungle King from Kingdom Hearts, except the Circle of Life is much stronger at the point in the game it is obtained than the Jungle King was.
The handguard of the Circle of Life is comprised of two large fangs that curve downward and do not connect to the pommel of the handle. The rainguard and Keychain are both lion heads, specifically the head of Simba as drawn by Rafiki in The Lion King movie.
The blade is a short wooden shaft that extends upwards a little, then curves into a backwards "C"-shape. The "C"-shape is wrapped in white cloth strips, and wooden spikes protrude from the wrappings, which serve as the teeth of the key. The chain of the Keychain seems to be a vine, rather than metal links.
It is named after the recurring theme throughout The Lion King.
The Circle of Life boasts a favorable strength boost of +4, but its real value lies in its innate ability, MP Haste, which reduces the amount of time Sora needs to regain his lost MP. It is a noteworthy substitution to the Ultima Weapon (when it is not available), but becomes eclipsed by the latter once it is obtained.