In accordance with one or more aspects, a toner cartridge may be detachably attached to an image forming device. The toner cartridge may be provided with a cartridge case. This cartridge case may be provided with a toner chamber, a cartridge side feed opening for feeding a toner from the toner chamber to the outside of the cartridge case, and a cartridge side return opening from the outside of the cartridge case to the toner chamber. The cartridge side feed opening and the cartridge side return opening may be offset along a horizontal direction. A bottom surface of the toner chamber may slant downward from the cartridge side return opening to the cartridge side feed opening.