Keaton Mask

The Keaton's Mask is an item found in both Ocarina of Time and Majora's Mask. The mask's appearance may be a reference to Pikachu, as well as looking reminiscent of a Kitsune.

Ocarina of Time
In Ocarina of Time the mask is the first mask you get in The Happy Mask Shop sidequest. It can be sold to the guard standing outside of the gate to Death Mountain in Kakariko Village for 15 rupees.

Majora's Mask
In Majora's Mask you get the mask by going to The Curiosity Shop Owner in Kafei's place after delivering the Letter to Kafei. Afterwards, if you wear the mask while cutting moving grass, like that found in North Clocktown, a Keaton will appear and ask you some questions. If you answer them all correctly, you will get a Piece of Heart.