An image forming system comprising a first device that can continuously discharge a paper and a second device that is located at a downstream side in a paper conveyance direction relative to the first device and is blocked from information on a paper conveyance in the first device, wherein the second device comprises: a paper introduction unit that introduces a plurality of papers including a first paper that is discharged from the first device and a second paper that follows the first paper; a printing setting acquisition unit that acquires, from the first device, information on a printing setting of the paper; a paper processing unit that performs a predetermined process on the paper; a paper conveyance unit that includes a paper conveying path and conveys the paper, along the paper conveying path, from the paper introduction unit to the paper processing unit; a paper detection unit that is located at a predetermined position on the paper conveying path that extends from the paper introduction unit to the paper processing unit and detects the paper that passes the predetermined position; a print cycle calculating unit that, based on information on a printing setting of the first paper and a time at which the first paper passes the predetermined position, sets a printing cycle that serve as a reference of a timing for the paper processing unit to start the predetermined process to the paper; a delay time calculating unit that, based on the printing cycle and a time at which the second paper passes the predetermined position, calculates a delay time from the printing cycle of the second paper; and a conveyance control unit that in accordance with the delay time, changes a conveyance speed of the second paper that is conveyed to the paper processing unit. a paper introduction unit that introduces a plurality of papers including a first paper that is discharged from the first device and a second paper that follows the first paper; a printing setting acquisition unit that acquires, from the first device, information on a printing setting of the paper; a paper processing unit that performs a predetermined process on the paper; a paper conveyance unit that includes a paper conveying path and conveys the paper, along the paper conveying path, from the paper introduction unit to the paper processing unit; a paper detection unit that is located at a predetermined position on the paper conveying path that extends from the paper introduction unit to the paper processing unit and detects the paper that passes the predetermined position; a print cycle calculating unit that, based on information on a printing setting of the first paper and a time at which the first paper passes the predetermined position, sets a printing cycle that serve as a reference of a timing for the paper processing unit to start the predetermined process to the paper; a delay time calculating unit that, based on the printing cycle and a time at which the second paper passes the predetermined position, calculates a delay time from the printing cycle of the second paper; and a conveyance control unit that in accordance with the delay time, changes a conveyance speed of the second paper that is conveyed to the paper processing unit.