Oni Kick is a move introduced in the first Tekken and is exclusive to Yoshimitsu and Kunimitsu. It was originally an unnamed basic left kick but was given a name in Tekken 4. It is sometimes called Ballerina Kick. Jin Kazama has a similar but unrelated move called the Spinning High Kick.
The user does a spinning roundhouse kick to knock their opponent over. If it connects with a standing opponent, it will send them into a spin. If the first kick connects on a counter hit, the opponent will spin even faster. From Tekken Tag Tournament onwards, if the first kick connects an airborne opponent, they will also spin in the air with the same speed as a counter hit.