The invention provides a novel luminescent nanosheet, and applications to that luminescent nanosheet. The invention also breaks down conventional common knowledge of nanosheet solutions to provide a nanosheet paint that makes use of a high-concentration nanosheet solution suitable for dispersion of a luminescent nanosheet or the like.The invention provides a luminescent nanosheet having perovskite octahedral crystals combined together in a planar configuration, characterized in that the octahedral crystals each have a multistacked crystal sheet structure wherein the octahedral crystals are multistacked over at least 3 high in the direction vertical to a sheet plane, and an element providing a luminescence center is solid-solubilized between the multistacked octahedral crystals (see FIG. 8).The invention also provides a nanosheet paint having a nanosheet dispersed in a disperse medium, characterized in that an X value in the following equation 1 found from the vapor pressure of the disperse medium and the concentration of the nanosheet is in a range of less than 4.9×106 to greater than 3.8×103: X=C×V4.01   1 where C is the concentration (M) of the nanosheet, and V is the saturation vapor pressure (torr) of the solvent at 25° C. and 1 atm.