1. A device controller connecting with multiple terminals and with at least one input-output device via a network, the device controller comprising: a reception controller configured to perform first authentication according to data input from a first terminal, which is one of the multiple terminals, and to cause the first terminal to obtain information on a specified series of processing based on a result of the first authentication; an input-output controller configured to perform second authentication according to data input from a second terminal, which is one of the multiple terminals, and to cause a specific input-output device selected out of the at least one input-output device to perform the specified series of processing, based on a result of the second authentication; and an operation log recorder configured to record at least part of operations performed by the user as the subject of the second authentication prior to the second authentication, as an operation log of the user, wherein the second authentication includes verification that a user as a subject of the second authentication is identical with a user as a subject of the first authentication, the input-output controller allows the specific input-output device to perform the specified series of processing when the second terminal is selected in advance for the specific input-output device, and the input-output controller refers to the record of the operation log of the user and allows the specific input-output device to perform the specified series of processing in response to the second authentication within a preset first time period since an instruction given for performing the specified series of processing, while deleting the information on the specified series of processing in the event of no second authentication within a preset second time period since the instruction given for performing the specified series of processing.