Lunar Harp
From Final Fantasy Wiki
The Lunar Harp is a Key Item in Final Fantasy VII. The Lunar Harp is used to "awaken" the Sleeping Forest, which allows the playing to pass through it. If the Harp is not used, the first screen will repeat infinitely. The item can be dug out in Bone Village. Specifically it is located at the top level, just southwest from the tent.
In Crisis Core, the Lunar Harp was an item that could be used in Materia Fusion for MP +10%, up to a maximum of 999%.
