Users collect a sphere of air in his free hand that mimicks the feel of a ball then fire it at the opponent just before hitting the real ball. By doing this, the opponent's timing is skewed, causing the racket to seemingly stop before hitting the real ball. When the air travels through the racket and the receiver tries to hit the ball, the ball hit is out.
It also appears that Gemini can also be referred to as a magnet shot and is an incomplete version of Keith's Bio-Magnetism.
Gemini seems to be exclusive to the The Prince of Tennis: Eikoku-shiki Teikyū-jō Kessen! movie.
Although Gemini refers to "twin player" form of tennis, where there is one fake ball and real one, Gemini can be hit with more than one air ball.
- Peter can hit triplets, or one real ball and two air formations.
- Xiu can hit Gemini on a serve. He also displays that he can hit four air-formations in addition to the original ball.
- Keith's completed Gemini, or magnet shot, is his Bio-Magnetism.
Several people have been seen countering Gemini.
Echizen Ryoma successfully counters Xiu's Gemini by allowing the air-ball to flip his racket, preventing him from losing momentum. This allows him to hit the ball normally, as if the air just passed right through.
It is shown by the members of Clack that one can simply lower his racket or dodge the air-ball to allow the Gemini to pass him or pass over his racket, thus avoiding it completely.