Provision of a technology capable of presenting information regarding derivative files secondarily derived and created from a leaked file, by retrieving the first leaked file, and capable of presenting personal information recorded on a computer accessible via a wide area network. There is provided an apparatus including a recording section for recording original data of a leaked file, an extracting section for extracting the original data and representations corresponding to information that should be prevented from being leaked and included in one or more files existing in a recording area to be investigated, an investigating section for investigating a degree of association between the file existing in the recording area to be investigated and the original data based on the extracted representations, and a presenting section for presenting information on a file created based on the leak.