Gratitude Crystal

are items in SS undefined. Link can obtain these crystals by doing good deeds to the various people he meets throughout his adventure. Upon doing so, the person that was helped will be overwhelmed with feelings of thankfulness, emitting enough energy to create 5 Gratitude Crystals. Link may also find fifteen Gratitude crystals at night in the islands of Skyloft, Pumpkin Landing, and Beedle's Island. After Link's Goddess Sword is upgraded to the Goddess White Sword, he may dowse for them after speaking to Batreaux.

Uses
There are a total of 80 Gratitude Crystals found throughout the game. Bringing them to Batreaux, who wants to use these items to become human, yield various rewards to the young hero, including upgrades for his wallet, satchels, and his Adventure Pouch.

Trivia

 * The Gratitude Crystals and the Star Fragment treasure item are both designed to resemble the Japanese candy Konpeitō. Konpeito are hardened sugar formed into star shapes and are well recognized in Japanese culture.
 * The Couple's Mask is also described to maintain gratitude.