Moon

In The Legend of Zelda: Majora's Mask, the Moon is a puppet of Majora's Mask during Link's adventure in Termina. By the power of Majora's Mask, it had been pulled from its orbit and destined crash into Clock Town, which would obliterate the town along with most of Termina.

History
Before the events of Majora's Mask, the Skull Kid ambushed the Happy Mask Salesman and took one of his precious masks, the Majora's Mask. Even though the Skull Kid was unaware of it, Majora's Mask gradually began to take control over him, turning his harmless pranks into acts with malicious intents behind them. Eventually, the mask completely embraced the Skull Kid's mind, and using him as a puppet, Majora's Mask pulled the moon from its orbit and set its course to crash into Clock Town. Once Link arrives in Termina, he finds out that he just has three days to prevent the moon from extinguishing all of Termina.

Along with his fairy companion Tatl, Link sets out to free the Four Giants in each of the temples found all over Termina. With the Giants free from their curse, the young hero and his fairy climb atop the Clock Tower on the Final Day to call upon the Giants using the Oath to Order. One by one, the Four Giants appear and stop the moon from its path of destruction.

In a turn of events, Majora's Mask realizes that the Skull Kid has become useless; thus, the Mask abandons the imp's body and transports itself inside the moon. With the moon now being possessed by the powerful Majora's Mask, it becomes too strong for the Giants to hold it back, for it threatens to continue with its plan of obliterating Termina:

"I... I shall consume. Consume... Consume everything."

- Moon possessed by Majora's Mask

While the Four Giants use all their might to try and sustain the evil menace, Link and Tatl decide to follow Majora into the moon. The two heroes battle against the powerful Majora and, once the malicious threat behind all of this is defeated, Link and Tatl are able to return to Termina just before the moon is overtaken by a bright light, never to be seen again.

Inside the Moon
Inside the moon is where the final battle takes place. It resembles a sunny, bright meadow, hazy like a dream. The only thing to break the scene is a single tree in the middle. Four children wearing each of the Boss Remains can be seen running around the tree; however, there is another child sitting beneath the tree wearing Majora's Mask. While the other Moon Children are running around and playing, the Majora child just stays seated under the tree.

A decision can be made whether to advance straight to the boss fight with Majora or to wait and complete four of the optional mini-dungeons that each Moon Child has prepared for Link. Depending on which Moon Child Link spoke to, each of these mini-dungeons resemble one of the four temples where the Boss Remains were obtained, and it will require the use of one of the transformation masks that Link possesses (e.g., talking to the Odolwa child will extensively require the use of the Deku Mask, and the mini-dungeon will have the theme of the Woodfall Temple. This is true for all except the Twinmold child, which doesn't require the use of a morph mask). However, the four mini-dungeons cannot be completed unless all of the masks have been obtained, with the exception of the Fierce Deity Mask. This is due to the fact that when Link talks to one of the Moon Children, he will ask that Link hand over a specific amount of non-transformation masks in order to enter the dungeon, and another specific amount to exit. If these requirements are met, the child will offer to play "hide and seek" with Link, who is then transported to the respective dungeon.

The dungeons are no more than a few rooms long, each containing a Gossip Stone revealing where to find each mask, as well as a Piece of Heart. At the end of the dungeon, the Moon Child can be found, and after Link gives him the required masks, he will be transported back into the sunny field, but the child will be gone.

After Link has talked to each child, completed each dungeon, and handed over all of his masks, all of the children will be gone except the one wearing Majora's Mask. If Link talks to him, he will offer to play a different kind of game: good guys against bad guys, mentioning that Link is the bad guy here. In return, the child will hand over the Fierce Deity Mask and immediately transport Link to the place where the final battle against Majora is to be held.

Other Appearances

 * In The Wind Waker's Nintendo Gallery, there is a sculpture of the moon in the background behind the counter.
 * Also, the face of the Skull Kid in Twilight Princess bears a slight resemblance to the face of the Moon.
 * In Super Smash Bros. Melee, the stage "Termina: Great Bay" has the Moon from Majora's Mask in the background. As the match continued, it would slowly descend (not affecting the match in any way). The Four Giants would then come and push the Moon back up. There is also a trophy of the Moon that could be collected in the game. Its trophy description briefly states the description of the inside of the moon.