Great Fairy Mask

The Great Fairy Mask one of the masks found in Majora's Mask, likely the second one. It is designed to look like a Great Fairy's head.

Location
The Great Fairy Mask is in the hands of the Great Fairy of Magic in North Clock Town. The method to obtain it is exactly the same one Link does in Deku form at the start of the game (when he is rewarded with magic power instead): Upon visiting the Great Fairy, Link will find that Skull Kid has shattered her into many Stray Fairies. He must find and bring back the missing one. During the day, the Stray Fairy can be found in the Laundry Pool. During the night, the Stray Fairy will be found in East Clock Town. Once Link takes the Stray Fairy back to the Great Fairy, she will give him the Great Fairy Mask so he can locate Stray Fairies easily in each dungeon and return them to their respective Great Fairies.

Uses
When the mask is worn, the hair on it will begin shimmering if there is a Stray Fairy in the room, and will also cause any Stray Fairies in that room to fly towards the wearer. If the Stray Fairy is trapped, as inside a bubble, it must be freed before it can approach.

The Happy Mask Salesman doesn't comment on the Mask's external beauty, as do some individuals, but instead remarks on its rarity, adding that "normally, you wouldn't be able to get one of those."

Trivia

 * It is one of the only four dynamic masks in the game (along with the Circus Leader's Mask, the Blast Mask, and the Bunny Hood), seeing as how the hair moves when running as well as its shimmering near stray fairies.