In an image-forming system, an image-forming substrate is used, which has a sheet of paper, and a layer of microcapsules coated over the sheet of paper. The layer of microcapsules includes at least one type of microcapsules filled with an ink. A shell wall of each microcapsule is formed of resin, which exhibits a temperature/pressure characteristic such that each of the microcapsules is squashed under a predetermined pressure when being heated to a predetermined temperature, thereby discharging the dye out of the shell wall. A printer, having a roller platen and a thermal head, forms an image on the substrate. The platen locally exerts the pressure on the microcapsule layer. The thermal head selectively heats a localized area of the microcapsule layer, on which the pressure is exerted by the platen, to a temperature in accordance with an image-information data, such that the microcapsules in the microcapsule layer are selectively squashed and an image on the microcapsule layer.