Key

A key is an object designed to open or close a lock. Keys appeared as items in several games from the Mega Man franchise with different shapes and purposes, usually as an item required to open a locked door to access a new area.

A typical key is a small piece of metal which slides into the keyway of the lock to open. Card keys are flat, rectangular cards that store a physical or digital signature, which can be used to disengage a card key lock. In the Mega Man Battle Network series, passcodes serve a similar purpose in the Cyberworld by giving access to an area.

Mega Man ZX
While performing missions to the Guardians, Vent / Aile obtain card keys that grant them access to new areas.

The game also contains one unused card key:

Mega Man ZX Advent
Grey / Ashe obtain two card keys to open doors in the Hunter's Camp. The game also contains an initialization key to activate a transerver. In a sidequest, the Hunter Richard lends a Firing Range Key to let the player fight an horde of.

Mega Man Legends
Keys are Special Items used by Mega Man Volnutt to open locks.

Mega Man Star Force

 * KeyMan
 * Andromeda Key

Mega Man Star Force 2
Mega Man must obtain the Whazzap Key (shortened WhzzpKey in-game, ナンスカへのカギ, "Key to Nanska" in Japan) to open the door to Whazzap.