An information processing system is provided. The information processing system comprises at least one processor configured to receive inputs of videos captured by a plurality of imaging apparatuses, detect a first person image appearing in a first video captured by a first imaging apparatus and a second person image appearing in a second video captured by a second imaging apparatus, associate a first person with a second person based on a first feature value of the first person and a second feature value of the second person, and provide an elapsed time from a first time point when the first person disappears from the first video to a second time point when the second person appears in the second video. The first feature value and the second feature value may include information based on histogram.