1. An image processing system comprising: an image reception unit that receives an image including an additional entry portion; an additional entry portion extracting unit that extracts the additional entry portion from the image received by the image reception unit; a concealment area specifying unit that specifies an area to be concealed in the image based on the additional entry portion extracted by the additional entry portion extracting unit; a concealment reason specifying unit that specifies a concealment reason based on one of operation information related to an operation for the image and a feature of the additional entry portion extracted by the additional entry portion extracting unit; an image concealment unit that conceals the area specified by the concealment area specifying unit in the image; and an image addition unit that adds concealment reason information related to the concealment reason specified by the conceal reason specifying unit to the image.