Example embodiments of the present invention include an information terminal comprising circuitry to: read, from a medium possessed by a user, first authentication information of the user; transmit an authentication request including the read first authentication information of the user to a first information processing apparatus that manages information regarding the user; receive, from the first information processing apparatus in response to the authentication request, second authentication information associated with the first authentication information, the second authentication information to be used for allowing the user to log in to a second information processing apparatus that resides on a network different from a network where the first information processing apparatus resides; and transmit the received second authentication information to the second information processing apparatus to request the second information processing apparatus for a service corresponding to the user.