The Bremen Mask is given to Link by Guru-Guru. It apparently originally belonged to a dog who was leader of an animal troupe. Link receives the Bremen Mask after listening to Guru-Guru's confession about how he stole it from the dog. This can only be done the night of the First or Second Day, since Guru-Guru and the rest of the Gorman Troupe will flee from Clock Town afterwards.
The Bremen Mask allows Link to play a marching melody, which makes domestic animals other than cows and horses follow Link, who leads them in a brisk march as he plays his Ocarina. The Bremen Mask can also be used in the fight against the Ikana warriors to confuse them and make them march along with Link, rendering them vulnerable to his attacks. It can also be used to make Cucco chicks grow into adults, which is required to obtain the Bunny Hood.