Yukinari Ookido, known as Professor Samuel Oak in the English and Italian versions, Professeur Chen in the French version, and Professor Carvalho in the Brazilian version, is a renowned Pokémon researcher, widely regarded as the best in his field. His role in the Pokémon games and anime is primarily that of a mentor to young Pokémon Trainers, serving as a valuable source of information and occasionally as a plot device. Among his many accomplishments, he is credited with inventing the Pokédex. Although proficient in all aspects of Pokémon knowledge, Professor Oak specializes particularly in Pokémon behavioral science.
In the "Pokémon 4Ever" movie, it is revealed that as a child, Samuel encountered a Celebi and traveled through time with it. He then arrived in the present day, where he befriended Ash. Following the defeat of Vicious, he returned to his original time period.










