Chord-playing input device, electronic musical instrument, and chord-playing input program

A computer-readable recording medium storing thereon an executable chord-playing input program for controlling a plurality of chord designating buttons arranged on a casing and assigned respectively with chords and a plurality of chord changing buttons arranged on the casing side by side with the chord designating buttons and assigned respectively with change methods for changing an assignment state of the chords for the chord designating buttons, when executed by a processor of a computer, performs operations comprising:

• generating sounding information to emit from a sounding part a sound of the chord corresponding to operation for the chord designating buttons and chord changing buttons, and
• generating display information to display on a display part a plurality of chord images corresponding to the chords assigned respectively to the chord designating buttons and a plurality of change method images corresponding to the change methods assigned respectively to the chord changing buttons in the same arrangement order as those of the chord designating buttons and chord changing buttons,
• wherein the plurality of chord designating buttons are each assigned with a first root and a first chord type that constitute the chord,
• at least one of the plurality of chord changing buttons is assigned with, as the change method, mutually different third and fourth chord types to change the assignment state, and
• when the first chord type corresponds to the third chord type, the first chord type is replaced with the fourth chord type to change the assignment state, while when the first chord type corresponds to the fourth chord type, the first chord type is replaced with the third chord type to change the assignment state.