The “anti-groping” stamps, manufactured by stamp-maker Shachihata Inc., allow victims of harassment to mark their assailants with invisible ink, and also provide a deterrent to would-be attackers.

Japanese developer Shachihata Inc released 500 of the chikan stamps yesterday. The anti-groping products cost ¥2,500 (£19) and leave a mark which can only be seen under ultraviolet light.

The "anti-groping" stamps, manufactured by stamp-maker Shachihata Inc., allow victims of harassment to mark their assailants with invisible ink, and also provide a deterrent to would-be attackers.