Sheet processing device and image forming system

A sheet processing device comprising:

• a stacking member configured to stack a sheet;
• a discharging member configured to discharge the sheet stacked on the stacking member;
• a discharging tray on which the sheet discharged by the discharging member is stacked;
• a pushing-out member configured to push out the sheet from the stacking member toward the discharging member by being moved in a pushing-out direction;
• and
• a controller configured to select, on the basis of information of the sheet stacked on the stacking member, whether to move the pushing-out member to which position of a first position and a second position positioned on a side downstream of the first position with respect to the pushing-out direction,
• wherein the controller is configured to select either the first position or the second position before sheets are stacked on the stacking member,
• wherein the stacking member comprises a guide,
• wherein the discharging member comprises a roller pair,
• wherein the pushing-out member comprises a guide, and
• wherein the controller comprises a processor or the controller comprises circuitry.