A processing device includes a communication interface configured to be communicably connected via a network with one or a plurality of terminal devices, a memory configured to store a program and music piece information that being associated with one or a plurality of users including a first user holding a first terminal device, and a processor configured to execute the program. The processor is configure to cause a game application to progress in the first terminal device in accordance with operation information input at the first terminal device, select first music piece information from the stored music piece information in accordance with a progress result of the game application, and transmit the selected first music piece information to the first terminal device via the communication interface.