Guru-Guru

Guru-Guru is a semi-recurring character in Ocarina of Time, Majora's Mask, and Oracle of Seasons. He is generally sentimental and kind with a very calm look on his face. However, when it comes to Link playing the Song of Storms, or when he is met with doubt in himself over things he's done wrong, his face can make sad, mad, and insane expressions. The name Guru-Guru is almost proven to be a reference to the Japanese onomatopoeia kuru kuru, referring to something going "around and around", which also happens to be Guru-Guru's chosen expression in Ocarina of Time.

Ocarina of Time
Guru-Guru is the hyper and easily angered Windmill Man of Ocarina of Time. Apparently he lives inside the windmill.. He stands in the windmill playing his phonograph and trying to make the windmill rotate at the right speed. A look of concentration can be seen on his face. When Link plays the Song of Storms, he becomes very agitated, and when the young hero plays it as an adult, he gets even more annoyed. During the credits, the Windmill Man is seen being held upside down by a few Kokiri, however, he still appears angry from to his meeting with Link in the Kakariko Windmill.

Majora's Mask
In Majora's Mask, Guru-Guru is the Gorman Troupe's musician. Guru-Guru is seen at night in the Laundry Pool area of Clock Town playing his phonograph since he has been kicked out of his room for practicing too loud. He is usually an extremely happy person, and long ago was a member of an animal troupe; however, he was jealous of the dog being the leader of the troupe, who could always get any animal to follow his command. As such, Guru-Guru stole the dog's mask, called the Bremen Mask. He gives Link the mask as a reward for listening to his story and to get rid of his guilt.

His theme song is the Song of Storms. He also appears during the day in the Stock Pot Inn in the room at the end of the hall. During the nighttime this room is occupied by the Gorman Troupe, and in the daytime, it is occupied by Guru-Guru and Marilla Rose of the Rosa Sisters.

Oracle of Seasons
He also appears in Oracle of Seasons where he stands by his windmill playing his theme song, although sounding a little different from the two games before. His only use is later in the trading sequence when Link gives him engine grease. In return, Guru-Guru hands over his phonograph, which is used to play for the Deku Scrub in the Tarm Ruins. This is not necessary if the player remembers how to get the Noble Sword.

Trivia

 * He is slightly similar to the Happy Mask Salesman, as both are constantly smiling and have brief moments of surreal rage.
 * Guru-Guru's relation to the Hurdy-Gurdy Man of The Minish Cap is unknown, but the Hurdy-Gurdy Man sports a grinding music box and the same facial hair.