Wario Land II is set after the events of Super Mario Land 3, where special agents from the Black Sugar Gang infiltrate Wario's castle and reclaim the stolen treasure. As a result, Wario finds himself tasked with cleaning up the mess he created.
As the main antagonist, Wario must navigate through levels, collecting coins while avoiding enemies. However, unlike in previous games, Wario has become immortal to a certain extent. When hit by an enemy, he loses his collected coins, but can transform into other versions of himself, such as Air Wario or Fire Wario, which grant unique abilities.
These transformations come with their own advantages and disadvantages. For example, Air Wario allows him to reach areas inaccessible in his normal form, while Fire Wario provides temporary invincibility. But these changes also disrupt Wario's progress, making it essential for the player to adapt quickly.