The invention provides an information processing system, an information processing device, an information processing method, and a storage medium that can extract group terminals from among a plurality of peripheral information processing terminals that have been detected, and calculate a peripheral degree of happiness. The information system comprises: a communication unit that receives identification information from a detection device that detects the identification information of surrounding terminal devices; and a control unit that extracts, as group terminal devices, a plurality of setsof identification information, received by the communication unit, representing a plurality of terminal devices detected by the detection device within a predetermined period of time, and that calculates the degree of happiness around the detection device in accordance with the extraction results.