A sheet separation device separates a two-ply sheet in which two sheets are bonded together at a portion. The sheet separation device includes a rotator, a nipping member opposite the rotator, to nip the two-ply sheet with the rotator, a conveyor to convey the two-ply sheet between the rotator and the nipping member, a winding member adjacent to the rotator, to wind the two-ply sheet around the rotator, and control circuitry. In winding the two-ply sheet, the control circuitry rotates the rotator at a first speed faster than a second speed at which the two-ply sheet moves to the rotator via the conveyor, and creates a difference in winding circumferential length between the two sheets, thereby separating the two sheets. The conveyor conveys the two-ply sheet with a bonded portion of the two-ply sheet being an upstream end or a downstream end in a conveyance direction of the two-ply sheet.