An information system accesses an internal network via a firewall from an information terminal of an external network. The information system includes a relay server provided in the external network; and a file server provided in the internal network. The file server includes a relay agent configured to manage a network connection between the file server and the relay server, and a file system configured to store desired data. The relay agent generates a thread based on a number of requests received by the relay server from the information terminal, acquires the request by using the generated thread, and transfers the acquired request to the file system. The file system identifies data corresponding to the transferred request, and outputs the identified data to the information terminal via the relay agent and the relay server.