To perform the glitch, at least one save file in which the player has not obtained Yuffie yet is required. The glitch is activated by getting a game over in any non-world map battle or in the Diamond Weapon boss battle, then reloading a save file on the world map and attempting to recruit Yuffie, without entering a field map in between the game over and the Mystery Ninja encounter.
After defeating Mystery Ninja and closing the battle spoils screen, instead of being warped to the field on which one may recruit Yuffie, the player is warped to where their previous game over occurred. If their previous game over was in a scripted battle, that battle will restart after the Mystery Ninja encounter. If their previous game over was in a random field map battle, they will be warped to the exact spot where the random battle was triggered but the random battle will not start over again.
The glitch can be used to skip large portions of the game as well as to replay most parts of the game for as often as desired. For instance, it allows one to skip Aeris's death, thus keeping her as a party member for the rest of the game. It may be used to fight Diamond Weapon to repeatedly gain the EXP and AP it yields. It can also be used to regain access to unrevisitable locations, like Gaea's Cliff. It can also be used to access the Debug Room.