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

An image forming system comprising a sheet processing apparatus that performs predetermined processing on a sheet or a sheet bundle, the sheet processing apparatus comprising:

• a conveying unit that conveys a sheet along a conveying path;
• an aligning unit that, each time a sheet is conveyed by the conveying unit, aligns the sheet;
• a stacking unit that reverses a conveying direction of a sheet to convey the sheet backward to a branch path branched from the conveying path, and stacks the sheet in the branch path;
• and
• a binding unit that binds a sheet bundle aligned by the aligning unit, in the conveying path.

A sheet processing method of performing predetermined processing on a sheet or a sheet bundle, the sheet processing method comprising:

• conveying, by a conveying unit, a sheet along a conveying path;
• aligning, each time a sheet is conveyed by the conveying unit, the sheet;
• stacking, during the aligning, a sheet in a branch path branched from the conveying path by reversing a conveying direction of the sheet to convey the sheet backward to the branch path;
• and
• binding an aligned sheet bundle stacked at the stacking, in the conveying path.