A performance system can include a primary unit and a secondary unit. The secondary unit is provided for an electronic musical instrument that can be set to a first mode that enables performance by a single individual and a second mode that enables performance by a plurality of individuals, has connecting portions enabling connection of one or a plurality of receivers having at least a receiving function, and is able to communicate with the primary unit. The performance can also include an determining portion for determining whether or not a plurality of the receivers is connected to the connecting portion, and a transmitting portion for transmitting, to the primary unit, a notification that the second mode has been set, upon determining that a plurality of the receivers has been connected to the connecting portion. The secondary unit can include a setting portion for setting the electronic musical instrument to the second mode upon a determination that a plurality of receivers has been connected to the connecting portion.