You can find Majora's Mask in a Treasure Chest (Floating Coliseum). Majora's Mask can be purchased (or repurchased once initally found for the first time) in the following shop locations: ...

Majora's Mask is definitely a strong contender for being the hardest of all The Legend of Zelda games; its three-day timer mechanic relies on a massive amount of trial and error if you want to save ...