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

A sheet processing apparatus comprising:

• a plurality of roller pairs configured to convey a sheet from upstream to downstream in a sheet conveyance direction, the plurality of roller pairs including,
• a first roller pair;
• a second roller pair downstream from the first roller pair in the sheet conveyance direction;
• and
• a third roller pair between the first roller pair and the second roller pair, the third roller pair configured to form a crease on the sheet;
• a single driving force generator configured to supply a driving force to the first roller pair, the second roller pair, and the third roller pair;
• and
• a drive transmission mechanism configured to transmit the driving force to the first roller pair and the second roller pair in a manner such that a rotation direction of the first roller pair is not switched even in a case in which a direction of the driving force is switched such that a rotation direction of the second roller pair is switched when the first roller pair and the second roller pair are driven by the driving force from the driving force generator.