Keyzer

A Keyzer, sometimes referred to as a Ghost Key, is a small levitating creature in Wario Land 4. It bears some resemblance to a Boo, although with a key for a nose. A Keyzer must be located by Wario in each of the 18 stages. A Keyzer is always found sleeping. Once found, it wakes up and follows Wario until he either loses all his health or exits the level via the vortex. The Keyzer then unlocks the sealed door that leads to the next stage, and the Keyzer disappears once it does so. Once the door is unlocked, the Keyzer cannot be found in that same stage a second time.

If Wario exits a stage without finding the Keyzer, his points and any jewel pieces collected will still be counted, but he will not be able to progress to the next stage. Wario is able to reenter any stage where the Keyzer has not been found.

In Crescent Moon Village, a ghost enemy shows an interest in a Keyzer, and it excitedly tries to steal him from Wario. The ghost's movement becomes faster after stealing the Keyzer, which may make it difficult for Wario to catch him. Wario simply has to touch the ghost to retrieve the Keyzer, although the ghost continues trying to steal it.

A Keyzer also appears in volume 28 of Super Mario-kun, on the page showing the chapter's end.