1. A character-recognition method comprising: imaging a character string; generating a grayscale image that corresponds to the character string; cutting out, from the grayscale image, individual characters in the character string; obtaining a coincidence of a character image that is being focused on for each of model images of a plurality of kinds of characters by sequentially focusing on cut-out character images to match the cut-out character images against the model images; and recognizing characters corresponding to the cut-out character images based on each coincidence, wherein a composite character model image comprising a pair of character elements arrayed along a width direction is registered while predetermined identification information is provided to the composite character model image, and wherein, in matching against the model image comprising the identification information, composite matching, in which an image of a range comprising the character image being focused and an adjacent unprocessed character image is matched against the model image comprising the identification information, is performed, and a combination of the two character images comprised in the composite matching target range is recognized as a character corresponding to the matched model image comprising the identification information when the coincidence obtained by the composite matching is larger than a predetermined reference value.