An image forming system according to an embodiment comprises a data creation section configured to create document data, and a print instruction section configured to send instructions to print the document data. The image forming section further comprises a printing mode determination section configured to determine a printing mode of the document data based on property information of the document data, and a selection section configured to select for printing the document data with one of a non-erasable image forming section and an erasable image forming section based on the determined printing mode.