In Japan, people visit shrines to pray for good fortune. For determining their fortune, they draw fortune-telling paper slips called Omikuji. The Omikuji contain predictions ranging from daikichi (“great blessings”) to daikyo (“curses”). As a novel, interactive fortune-telling system, we propose the “Fortune Air.” According to the person’s interactions and a random value generated by the measured resistance of a leaf from a tree in the shrine, in real-time, a unique fortune is determined. Then the fortune-air system visualizes the fortune using one of the four patterns generated by double vortex rings: merging, rebound, disappearance and no-interference. After the visualization, the paper containing the fortune is printed by a thermal printer. In this study, we conducted an experiment for determining the parameters for controlling the four patterns of double vortex rings. From the results, we confirmed that the distance between the air cannons and a combination of the air pressure as well as the angle of the two air cannons, are the parameters to control the four patterns generated by the vortex rings. Using the results, we implemented a prototype system for the fortune-air and evaluated the entertainment value provided by the interactive system to enhance the praying experience.