The tapu—Tapu Koko, Tapu Lele, Tapu Bulu, and Tapu Fini—are a quartet of Legendary Pokémon first discovered in the Alola region. They serve as the guardian deities of each of Alola's four main islands: Tapu Koko on Melemele Island, Tapu Lele on Akala Island, Tapu Bulu on Ula'ula Island, and Tapu Fini on Poni Island. Alola's island kahunas are each chosen by their island's guardian deity. Grand trials are often done in favor and praise of the Tapu. The Tapu are known to be very kind in certain situations, lending gifts, but they can also be very cruel, destroying certain locations or harming others when feeling angered. According The Light of Alola, a book found in the Malie Library, the tapu fought off against a beast from another dimension and lost. They were rewarded with the Tapunium Z, their signature Z-Crystal. The beast then created multiple Cosmog for the tapu to take care of and protect as they grow up before returning to Ultra Space.