A bundling mechanism creates a sheet bundle including N sheets including an M-th sheet to be included in a k-th booklet and a first sheet to be included in a k+1-th booklet. The k is an integer from 1 to L?1. The M is not a multiple of N. A adhesion mechanism bonds together a preceding sheet and a subsequent sheet stacked at a stacker, except for the M-th sheet to be included in the k-th booklet and the first sheet to be included in the k+1-th booklet.

A sheet thermocompression apparatus for bonding a plurality of the sheets to one another, and configured to be compatible with the sheets with a plurality of prescribed sizes. The apparatus includes a loading portion to be loaded with the bundle of sheets each including the adhesion layer formed thereon and a thermocompression unit. The thermocompression unit includes (i) a pressing member pressing the bundle of sheets loaded on the loading portion in a loading direction of the sheets, a longitudinal direction of the pressing member is a direction along one edge of the sheets loaded on the loading portion, (ii) a heating source heating the pressing member, and (iii) a temperature measuring sensor arranged at a position not overlapping a minimum sheet with a minimum size of the prescribed sizes loaded on the loading portion in the loading direction, and detects a temperature of the heating source.

A sheet processing apparatus includes a center folder, a back-crimp binder, and circuitry. The center folder performs a center-folding process to form a fold portion on a sheet bundle including multiple sheets. The back-crimp binder includes a back-portion former and a crimp binder. The back-portion former forms a back portion of the fold portion on the sheet bundle subjected to the center-folding process. The crimp binder performs a crimp-binding process on the back portion of the sheet bundle subjected to the center-folding process. The circuitry is to cause the back-crimp binder to form a crimp mark parallel to the fold portion on the back portion of the sheet bundle.

A sheet processing apparatus includes: a center-folder to perform a center-folding process on a sheet bundle including multiple sheet materials; a back-crimp binder to: form a back portion on the sheet bundle subjected to the center-folding process; and perform a crimp-binding process on the back portion; and a controller configured to: cause the center-folder to perform the center-folding process; and cause the back-crimp binder to perform the crimp-binding process on the back portion while forming the back portion on the sheet bundle in the crimp-binding process.

A sheet bonding apparatus includes a pressurizing member configured to pressurize a sheet stack, a receiving member configured to receive a pressurizing force of the pressurizing member and nip the sheet stack together with the pressurizing member, a heating portion configured to heat the pressurizing member, a pressurizing mechanism configured to press the pressurizing member against the sheet stack, and an inclination correction mechanism configured to correct relative inclination between the pressurizing member and the receiving member in a case where the pressurizing member pressurizes the sheet stack.

An image forming system includes an image forming apparatus and a sheet processing apparatus having a stacking unit, a moving unit, and a thermal compression bonding unit. The stacking unit includes a stack of plural sheet having an adhesive layer for bonding the plural sheets together. The thermal compression bonding unit includes a heating member having a heat generation area. In a case where a length of the adhesive layer regarding a longer-side direction of the heating member is greater than a length of the heat generation area, an entire area of the adhesive layer on the plural sheets is heated and pressed by applying heat and pressure to the adhesive layer more than once while changing, via the moving unit, a relative position of the plural sheets having been conveyed onto the stacking unit and the heat generation area regarding the longer-side direction of the heating member.

A sheet processing apparatus includes: a center-folder to perform a center-folding process on a sheet bundle including multiple sheet materials; a back-crimp binder to: form a back portion on the sheet bundle subjected to the center-folding process; and perform a crimp-binding process on the back portion; and a controller configured to: cause the center-folder to perform the center-folding process; and cause the back-crimp binder to perform the crimp-binding process on the back portion while forming the back portion on the sheet bundle in the crimp-binding process.

A booklet making apparatus is manually fed and receives a sheet bundle constituted by a plurality of sheets having an adhesive layer of toner, executes heat processing for heating the adhesive layer in the sheet bundle, which has been manually fed into the receiving unit, and executes press processing for pressing the adhesive layer in the sheet bundle in parallel with the heat processing.