1. A document processing apparatus comprising: a document information obtaining unit that obtains document information created using at least two applications; an image generating unit that generates a document image based on the document information; an area dividing unit that divides the document information into areas for each of the applications; a determining unit that determines whether a divided area is a character extractable area from which a character code can be extracted, for each of the areas; a first character information extracting unit that extracts, for a first area that is an area determined to be the character extractable area, first character information from the area; a second character information extracting unit that extracts, for a second area that is an area not determined to be the character extractable area, a character code by performing a character recognition processing on the document image as second character information; and a storing unit that stores therein the first character information, the second character information, and at least one of the document information and the document image in association with each other.