Hap Ki Do   Hap Ki Do was introduced by Choi Yong-Sul. The term Hap Ki Do translates to way of coordinated energy. We use other peoples energy and motion to work against them. Hap Ki Do came from Aiki-Jitsu, an art passed from Takeda Sensei down to Choi-Yong Sul as well as Aikido's Ueshiba and Judo's Kano Doju-nim Choi-Yong Sul