Toner, premix agent, and agent container

A toner comprising:

• a binder resin, and
• a release promoter,
• wherein the binder resin contains at least a crystalline polyester resin and a non-crystalline polyester resin,
• wherein a value of W/R is in a range of 0.045 to 0.850 where W denotes a height of a third bottom peak in an infrared absorption spectrum of the crystalline polyester resin and R denotes a height of a maximum top peak in an infrared absorption spectrum of the non-crystalline polyester resin and each of the infrared absorption spectra is measured by an infrared spectroscopic method (KBr method) using a Fourier transform infrared spectrometer,
• wherein the toner is used as a toner contained together with a carrier in a premix agent which is a developer containing the toner and the carrier previously mixed together before shipment, and
• wherein the premix agent is used in an image forming apparatus which comprises:
• a latent image bearing member,
• a developing device for developing a latent image on the latent image bearing member with the developer containing the toner and the carrier, and
• an agent supplying unit configured to supply the premix agent to the developing device.