Stone Mask

The Stone Mask is one of the most valuable masks in Majora's Mask. The mask prevents most non-boss enemies from detecting Link. Link can therefore walk through most of Termina without worrying about being attacked.

Obtaining the Mask
To receive this mask, you must use the Lens of Truth to find the invisible soldier Shiro in Ikana Canyon, and he will give you a request. He will ask that you cure him of his ailments; this is not done with the Song of Healing, however, but rather with a Red Potion. Once you have given him one, he will give you the Stone Mask in return.

Trivia

 * Even though the Blue Potion heals, Shiro will not accept it.