The Great Fairy Mask is given to Link by the Great Fairy of Magic in North Clock Town. Link obtains the mask if he returns the Great Fairy's missing Stray Fairy while in human form. During the day, the Stray Fairy can be found in the Laundry Pool. During the night, it will be found in East Clock Town. Once Link brings the Stray Fairy back to the Great Fairy, she will give him the Great Fairy Mask so that he can locate Stray Fairies easily in each dungeon and return them to their respective Great Fairies.
When worn, the hair of the mask will begin to shimmer if there is a Stray Fairy within a room, and will also make any Stray Fairies in that room fly towards Link if he is close enough. If the Stray Fairy is trapped, such as inside a bubble, it must be freed before it can approach.
The Great Fairy Mask is one of the only four dynamic masks in the game (along with the Troupe Leader's Mask, the Blast Mask, and the Bunny Hood), as the hair will move when Link runs and shimmer when there are Stray Fairies nearby.
Link obtaining the Great Fairy Mask in Majora's Mask
Great Fairy Mask from Majora's Mask
↑"Young one! Please hear my plea! I have been broken and shattered to pieces by the masked Skull Kid. Please find the one Stray Fairy lost in town, and bring her to this Fairy Fountain." — Great Fairy (Majora's Mask)
↑"Please, hear my plea! The masked Skull Kid has broken me apart and scattered my pieces! Please find a way to return me to the Fairy Fountain in North Clock Town." — Stray Fairy (Majora's Mask)
↑"Kind young one... Scattered about the four temples of this land are Stray Fairies like myself. Please, somehow find the Stray Fairies and return them to their fountains. Surely, they too will add to your strength. Allow me to grant you something good so that the Stray Fairies will not fear you." — Great Fairy (Majora's Mask)