In a state where an extended input device is secured to a data transmission device, an image capturing unit of the data transmission device captures an image of a light emitting unit that emits light, an image of which is allowed to be captured by the image capturing unit in accordance with a user input and/or a user operation, and data generated based on at least the captured image is transmitted to an information processing apparatus. The information processing apparatus executes an information process based on the transmitted data.