Prof. Kukui is a character in Pokemon Sun and Moon, and Alola's resident Pokémon expert. He is a passionate man who specializes in Pokémon moves. He is married to Prof. Burnet.
He is also known as The Masked Royal (Royal Mask in the Japanese version), a famous masked wrestler and star of the Battle Royal Dome.
Kukui later creates Alola's own Pokémon League, and is the last challenge the protagonist overcomes before becoming the League's first champion.
In the anime, Kukui is a teacher at the Pokémon School that Ash attended. He let him stay at his house.