Sheet processing apparatus, image forming apparatus, and image forming system

A sheet processing apparatus for laminating two sheets and a sheet medium inserted in two sheets, the sheet processing apparatus comprising:

• an inserter configured to insert the sheet medium into the two sheets;
• a heat presser configured to heat and press the two sheets into which the sheet medium is inserted;
• a temperature detector configured to detect a temperature of the heat presser;
• an information acquisition device configured to acquire information on the two sheets and the sheet medium;
• and
• control circuitry configured to
• set a fixing temperature of the heat presser in accordance with the information of the two sheets and the sheet medium acquired by the information acquisition device,
• cause the heat presser to wait until the temperature of the heat presser detected by the temperature detector falls within a proper fixing temperature range after the sheet medium is inserted into the two sheets by the inserter;
• and
• cause the heat presser to start heating and pressing the two sheets into which the sheet medium is inserted, when the temperature of the heat presser detected by the temperature detector reaches a proper temperature.