The "Sacred Stone" (御神石のお守り, O Jinseki no omamori, roughly "Sacred Stone Amulet") is a special charm used by Miku in Fatal Frame III: The Tormented. Using it allows her to slow the movement speed of ghosts. Since the ghosts move more slowly, it is easier to dodge attacks or aim in the Shutter Chance or Fatal Frame.
The Sacred Stone cannot be used if its meter drops to 0. However, if Miku euther damages a ghost or receives damage, the Sacred Stone meter replenishes. The higher her level, the faster it replenishes and the longer its duration of effect.