Hero's Key

, also known as Hero Keys, are items in.

Location and Uses
A FS: from the NaN Great Fairies of FS:, FS:, and FS: are required to enter the hero's door of FS:.

They are obtained after first finishing the FS: door of FS:, then completing the FS:, FS:, and FS: NaN Stages each with a minimum of 5000 NaN Rupees.

Trivia

 * In, FS: isn't present within single-player mode. As only a limited number of sources exist on each randomly-generated map, obtaining enough NaN Rupees for a FS: often requires repeatedly defeating respawning enemies.