An information processing system includes at least one information processor, an output data reception part configured to receive output data or output target data via a network, a determination part configured to determine whether user identification information, which is to be correlated with the received output data or output data generated based on the output target data, is specified from user information stored in a user information storage part, a storing part configured to store data identification information and the received or generated output data in correlation with each other in a data storage part when the user identification information is not specified; a notification part configured to give notice of the data identification information via the network; and a transmission part configured to transmit, via the network, the received or generated output data correlated with the user identification information or the data identification information received via the network.