A battery-state monitoring system for precisely and efficiently estimating the state and service life of each of a plurality of storage batteries while suppressing variations in voltage between the batteries in a large-scale power-supply system that is provided with the storage batteries charged with power generated by utilizing natural energy is provided. A scene of a portion of the simulated environment is displayed from a camera point of view on a video display. The key cap can be displaced vertically into three active positions and horizontally into four contact positions, giving rise to twelve distinct output data signals for inputting to the electronic device.