A gaming machine provides an operation unit, a display unit, and a control unit. The operation unit is an operation of the player. The display unit is operably coupled to the operation unit and is configured to display a symbol display area. The symbol display area including a plurality of cells arranged in a grid having a plurality of rows and a left plurality of columns and a right plurality of columns. Each column in the left plurality of columns being associated with a mirror column in the right plurality of columns. The control unit is operably coupled to the operation unit, the display unit is configured to initiate a game in response to player operation, and to establish an outcome of the game. Upon detection of a trigger condition, the symbols displayed in the cells of one of the columns are copied to the cells in a mirror column.