The Majora’s Mask Official Soundtrack will be releasing on October 7th, 2015 for Japan. The soundtrack will come with 113 tracks. All but one are the original tracks, and the new track that was made for the extra ending sequence in The Legend of Zelda: Majora’s Mask 3D is included. All of the songs have been remastered for the best audio quality and the package includes two discs, an 8-page booklet, a poster, and a rubber key chain of Majora’s mask.
The OST is being released by Tablier Communications and their Symphony No. 5 label. The soundtrack was originally released after the game came out in 2000, and was also available for Club Nintendo members in 2013. There is no official word on if the CDs will release in North America you can always import. You can see an image of the keychain below as well as the poster art.