The present invention provides a display medium comprising a display layer which selectively displays white or black color, and a light-modulating layer provided on the display layer including mobile fine particles which show coloration in a dispersed state, a display device using the display medium, and a display method using the display medium. The monitored data is analyzed to generate one or more content identifiers. The first connector is installed in the slot. The small-diameter cylindrical portion includes a deformation limiting portion that protrudes farther than other parts of the small-diameter cylindrical portion so as to oppose the oblique reduced-diameter portion.