From Kirbypedia

English Name:	Rainbow Drop
Japanese Name:	虹のしずく Drop of Rainbow Rainbow Drop
First Game:	Kirby's Dream Land 2
Type:	Collectable

An item in Kirby's Dream Land 2. Kirby must collect all seven from various levels in the Rainbow Islands in order to bring forth the Rainbow Sword to defeat Dark Matter.

These glistening pieces are sealed away in hidden areas at each of the seven levels. They are typically held behind a barrier that can only be broken with the use of a certain Copy Ability or ability combination with an Animal Friend. Some are more involved puzzles and require a series of abilities and trading between friends in order to acquire them.

If all seven Rainbow Drops are not obtained when King Dedede is defeated, the Rainbow Sword is never summoned to draw out Dark Matter, and the final battle never takes place. This earns the player the "bad" ending of the game.

Collectibles

Sparkling Star - Rainbow Drop - Crystal Shard - Mirror Shard - Heart Star Boss Battle Badges - Copy Palette Style - Ghost Medal - Graphic Piece - Musical Score - Secret Door Key - Secret Map - Sound Player - Spray Paint - Star Seal - Strawberry Shortcake - Treasure Chest - Vitality Piece