An image forming apparatus includes an image sensor configured to capture image data and a controller operatively coupled to the image sensor. The controller is configured to receive, from the image sensor, a requesting user image of a requesting user who requests authentication to use the image forming apparatus. The controller is configured to transmit the requesting user image to a terminal associated with an authenticating user that is authorized to authenticate the requesting user. The controller is configured to acquire, from the terminal, an authentication result indicating whether the authenticating user authenticates the requesting user to use the image forming apparatus.