This is a picture book set for young children to learn math in a fun way. The box has some damage. The books have not been used by the child after purchase. I checked the books before listing them, and there are no noticeable markings or folds. - Series Name: Sansu Daisuki (I Love Math) - Number of Volumes: Complete set of 10 volumes - Author: Hiroshi Toyama - Publisher: Nihon Tosho Center - Target Age: Approximately 3 years old to lower elementary school grades