A data transmission device that includes an image capturing unit and transmits data generated based on an image captured by the image capturing unit is allowed to be located at a case while at least a part of the data transmission device is accommodated in the case, such that an image capturing direction of the image capturing unit is directed toward an inner space of a case main body. An image capturing target member movable in the inner space of the case main body in accordance with an operation made from outside of the case main body is located at a position where an image of the image capturing target member is allowed to be captured by the image capturing unit. Based on the transmitted data, an information process is executed.