Ash, his mother, Mimey, and Pikachu arrive at Melemele Island in the Alola region on vacation to deliver a Pokémon egg to Professor Oak's cousin, Samson Oak. While exploring for new Pokémon, Ash and Pikachu stumble upon the Pokémon school, of which Samson is the principal, and meets three students: Mallow, Lillie and Sophocles, as well as Professor Kukui. While helping defend the school from a group of Team Skull grunts, Ash witnesses another student, Kiawe, perform a powerful Z-Move with his Pokémon to drive the grunts away. The night before Ash and his mother are due to return home, the Melemele Island guardian Pokémon Tapu Koko, who has been watching Ash, appears to him and gives him a Z-Ring that will enable him to perform his own Z-Moves. With his mother's permission, Ash decides to stay in Alola and enroll in the Pokémon school to learn more about Alolan Pokémon.