An example game system includes a main body apparatus and a game controller. The game controller has an analog stick, a memory storing correction parameter information including a first manufacturing process correction parameter value determined in a manufacturing process in connection with the analog stick, a first user correction parameter value determined in accordance with an operation by a user onto the analog stick, and a first model adjustment value corresponding to a model of the game controller, and a first control circuit transmitting the correction parameter information to the main body apparatus. The main body apparatus has a second control circuit which selects any of the first manufacturing process correction parameter value and the first user correction parameter value and performs game processing based on the selected correction parameter value, the first model adjustment value, and input data from the analog stick.