Medium processing apparatus and image forming system

An image forming system comprising:

• an image forming device to form an image on a medium;
• a stacker to stack media conveyed from and passed through the image forming device in a conveyance direction;
• a first direction aligner to align a position of the media on the stacker, in the conveyance direction;
• a second direction aligner to align a position of the media on the stacker, in a main scanning direction orthogonal to the conveyance direction,
• the second direction aligner contactable with the first direction aligner to move the first direction aligner;
• a binder to bind a media bundle of the media on the stacker;
• a drive source to move the second direction aligner in:
• one of the main scanning direction as a first-side direction to move the first direction aligner;
• and
• another of the main scanning direction as a second-side direction opposite to the first-side direction;
• and
• a switch to switch the first direction aligner between:
• a first state in which:
• the first direction aligner is allowed to move in the first-side direction by the second direction aligner;
• and
• the first direction aligner is restricted to move in the second-side direction;
• and
• a second state in which the first direction aligner is allowed to move in the second-side direction.