The Legend of Zelda: Majora's Mask Walkthrough

Majora's Mask p.8

Day
During the day, it can be found in the Laundry Pool in the southwest corner of Clock Town. Hop across the water and touch it to retrieve it.

Night
During the night, it can be found in East Clock Town in the middle of the square; you can't miss it. It's too high to get by walking up though, so you'll have to use the nearby Deku Flower and fly into it to retrieve it.

Once you've acquired the Stray Fairy, (another big-headed individual similar to yourself, if a bit shinier) return to North Clock Town and enter the cave on the left side. It will then combine with the others in the spring to become a large scandalous female known as the Great Fairy of Magic. They look much less obnoxious than they did in Ocarina of Time. Anyway, she'll give you Magic Power, allowing you to shoot bubbles with B. Sweetness! She also gives you a clue to finding the Skull Kid, saying to go to the Observatory next. Good to know. She also reminds you to come back when you have returned to your old self. What do you think she has in mind?