Master Leon de Heus (레이온 더 후스, 8th dan) is master Ko Baek-yong foremost student. In 1989 master Ko Baek-yong and Leon met when master Ko accompanied Myung Jae-nam kuksanim to a seminar in the Netherlands. It was Leon’s father, Tijmen de Heus, who told master Ko Baek-yong that his son dreamed of training in Korea, and because master Ko Baek-yong spoke English if it would be possible to visit his gym. In the summer of 1991 Leon traveled to Korea for the first time. Six weeks he spent with master Ko Baek-yong. It was the start of a deep relationship.
In the following years Leon traveled to Korea frequently and master Ko Baek-yong visited the Netherlands. Leon de Heus gathered a group of like-minded instructors in the Netherlands and together the founded the Nederlandse HKD Federation (Dutch HKD Federation). Leon became the head-instructor of this federation. In 2002 another dream of Leon was realized with the opening of his own fulltime hapkido training center. This training center acts as the headquarters of the Dutch HKD Federation.
In 2017 Leon was promoted to the rank of 8th dan by master Ko Baek-yong.