An information processing unit includes: a receiving unit which receives, via a communication network, first specifying information which is used by a content source to specify the content, from a display device which receives and displays broadcast content; a converting unit which, upon retrieval request from the display device for related information which is related to the content, converts the first specifying information into second specifying information, which is used by a source of the related information to specify the content; a retrieval controlling unit which transmits the second specifying information to a retrieval device, which retrieves the related information based on the second specifying information, via the communication network and controls retrieval of the related information; and a providing unit which provides the display device with the related information acquired from the retrieval device via the communication network upon retrieval request for the related information to the retrieval device.