According to one embodiment, a method for erasing an image includes erasing an image formed using a toner containing at least a binder resin, an electron donating color developable agent, and an electron accepting color developing agent by heating for 10 seconds or less. A color difference E between a region where the image is erased and a paper is 5 or less.

A developer according to an embodiment includes a toner having a color erasable by heating and a carrier. The carrier includes a core portion and a coating portion covering at least 50% of the core portion. The coating portion includes an additive agent which suppresses an increase in electrification due to friction between the toner and the carrier. The additive agent has a white color.

A reversibly allochroic toner contains a binder resin and a colorant. The colorant reversibly switches between first and second color states in response to temperature changes. The colorant exhibits a hysteresis in a temperature-color state curve thereof in which the following relationships are satisfied.

Tr<T.sub.L2<T.sub.L1<T.sub.H1<T.sub.H2<Tg

T.sub.H250 C.

20 C.Tr30 C.

where, T.sub.H1 is a temperature at which the colorant starts to change from the first color state to the second color state, T.sub.H2 is a temperature at which the colorant completely changes to the second color state, T.sub.L1 is a temperature at which the colorant starts to change from the second color state to the first color state, T.sub.L2 is a temperature at which the colorant completely changes to the first color state, and Tg is a glass transition temperature of the binder resin.

A method for producing a developing agent including preparing a dispersion liquid containing first fine particles containing a binder resin and second fine particles containing a color developable compound, a color coupler, and a color eraser, and aggregating the first and second fine particles in the dispersion liquid to form aggregated particles.

A method of producing an emissive toner composition including selecting a photoluminescent agent, a charge control agent, and one or more additives and combining the photoluminescent agent, charge control agent, and one or more additives to form an emissive toner composition that when printed to produce an image component on a substrate, the emission spectra of the image component for irradiation with a first excitation energy includes only dominant emission peaks corresponding to one or more dominant emission peaks of the photoluminescent agent. The photoluminescent agent is selected such that it emits light having one or more dominant emission peaks in a first emission spectral region when irradiated with the first excitation energy. The charge control agent and one or more additives are selected such that they do not emit light in the visible spectrum when irradiated with visible light and does not emit light in the first emission spectral region when irradiated with the first excitation energy.