A toner is provided, which has a toner particle that contains a binder resin, and organosilicon polymer particle on a surface of the toner particle. A methanol concentration a (vol %) of the organosilicon polymer particle in a wettability test and a methanol concentration b (vol %) of the toner particle in a wettability test satisfy Expression (I) below:
|a−b|≤25  (I), and an adhesion index of the organosilicon polymer particle on a polycarbonate film, calculated on the basis of Expression (II) below, is not more than 3.5:
Adhesion index=area ratio c of the organosilicon polymer particle having migrated to the polycarbonate film/coverage ratio d of the organosilicon polymer particle on the surface of the toner particle×100  (II).

A toner comprising a toner particle comprising a resin A, and an external additive A, wherein the resin A is a resin represented by formula (1) below, the resin A is present at the surface of the toner particle, the external additive A is a fine particle containing silicon, the average value of the shape factor SF-1 of the external additive A is from 105 to 120, the average value of the shape factor SF-2 of the external additive A is from 100 to 130. ##STR00001##

A toner contains mother toner particles each containing a binder resin, a releasing agent, and a charge control agent and an external additive containing hydrophobized polymethylsilsesquioxane particles with an average particle diameter of from 0.050 to 0.150 μm, wherein the mother toner particles have an average circularity of 0.95 or less.

A core-shell particle includes a core, and a shell on a surface of the core. The core includes a crystalline release agent. A value of a sum of a number-average value of Feret diameter of the core-shell particle and a standard deviation of the Feret diameter of the core-shell particle is 20 to 500 nm. The shell comprises an organosilicon polymer. In a differential scanning calorimetric measurement of the core-shell particle, a maximum endothermic peak is present when a temperature is raised from 30° C. to 120° C. at 10.0° C./min, a maximum exothermic peak is present when the temperature is lowered from 120° C. to 30° C. at 10.0° C./min, and Tc (° C.) is at least 5° C. lower than Tm (° C.) where Tm is a peak temperature of the maximum endothermic peak and Tc is a peak temperature of the maximum exothermic peak.

A toner containing a toner particle, wherein, when a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tanδ50° C.(1), and a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 30° C. and a relative humidity of 50% RH after the impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tanδ30° C.(2), tanδ50° C.(1) is from 0.015 to 0.050, the relationship tanδ50° C.(1)>tanδ30° C.(2) is satisfied, and tanδ30° C.(2)/tanδ50° C.(1) is from 0.25 to 0.66.

An electrostatic image developing toner includes a toner particle, an external additive A, and an external additive B. At least the external additive A is present on the surface of the toner particles. At least the external additive B is present on the external additive A. The number of peaks of the external additive B on the external additive A is 5 or more and 100 or less per 30 μm peripheral length of the toner particle, the peaks having a height from the surface of the toner particle of 80 nm or more and 250 nm or less.

Toner contains toner base particles and an organosilicon polymer on the surface of the toner base particles. After a toner image is transferred from an intermediate transfer belt to a transfer material, residual toner on the intermediate transfer belt is collected into a belt cleaning device by a blade. A CPU executes supply control of supplying toner from a developing device toward the blade via a photosensitive drum and via the intermediate transfer belt on the basis of a counter accumulated value that correlates with an amount of organosilicon polymer adhering to the blade.

A resin composition includes: a resin having a first group capable of forming at least two hydrogen bonds; and a photoisomerization compound having a second group capable of forming at least two hydrogen bonds complementarily with the first group and having a moiety that is reversibly isomerized by light.

A photoresponsive polymer that is fluidized by light irradiation and reversibly non-fluidized and contains a structural unit represented by a general formula (1) shown below:

##STR00001## wherein each substituent is defined as described in the specification.

A compound that is fluidized by light irradiation and reversibly non-fluidized and is represented by the following general formula (1):

##STR00001##

In the general formula (1), Ar.sub.1 and Ar.sub.2 each independently represent an aromatic hydrocarbon group optionally having a substituent or an aromatic heterocyclic group optionally having a substituent, and Y, Z.sub.1, and Z.sub.2 each independently represent a hydrogen atom or a lower alkyl group.