A data processing system includes a data processing apparatus providing a service to a service using apparatus and the service using apparatus that includes an authentication requesting unit that requests the data processing apparatus to authenticate the user by user specifying data input via an input screen, an obtaining unit that obtains, when the user is successfully authenticated, association data associated with the user specifying data from the data processing apparatus to store in a storage unit, and an accepting unit that displays, when the association data is stored in the storage unit, a user list of users specified from the association data in the input screen, reads out, upon a selection of a user from the user list, a part of the user specifying data from the association data corresponding to the selected user, and accepts an input of information except the read out part from the input screen.