Original sentence: While he was a university student, he began studying martial arts with the renowned World Karate Grand Master Masutatsu "Mas" Oyama (who he later played in a trilogy of films), leading to his becoming a first degree black belt
Edited sentence: While he was a university student, he began studying martial arts with the renowned World Karate Grand Master Masutatsu "Mas" Oyama (whom he later portrayed in a trilogy of films), leading to his becoming a first-degree black belt