Joy Butterfly

Joy Butterflies are special butterflies filled with blue color. They appear as you fuse Kinstones with people. They have different abilities, such as increasing your digging speed, etc.

Joy Butterflies are small and pretty slow and therefore are easy to catch. Just walk over them and you have the butterfly.

Quote from The Legend of Zelda: The Minish Cap Joy Butterfly figurine: "A rare butterfly said to bring happiness to those who catch it. If you see one on your journeys, try to grab it!"

Trivia

 * Joy Butterflies could be a reference to the fact that in The Wind Waker, Joy Pendants are shaped like butterflies.