Printing system, controller, printing method and storage medium

A controller of a printing system creates imposed printing data in which a plurality of printing data for representing a printing image on one side of a sheet printed) are imposed (i.e., data to represent printing images covering a single page of a printed matter). The controller also determines a sequence of output of imposed printing data with respect to a printing apparatus, on the basis of information about pickup of sheets in a bookbinding apparatus, and the controller then outputs the imposed printing data to the printing apparatus in a sequence of output so determined. The printing apparatus prints on the sheets printing images represented by the imposed printing data, in accordance with the sequence inputted from the controller. The sheets printed by the printing apparatus are then picked up and bound. This eliminates that any operator is required to impose a plurality of printing data in consideration of the pickup of sheets in the bookbinding apparatus. It is therefore possible to provide a printing system that does not require any operator to have such a skill.