A shamoji is a Japanese rice paddle, rice scoop, or rice spatula. It’s a standard tool to handle cooked rice, such as for mixing and serving. It can be made from plastic, wood or bamboo. If you buy a rice cooker, a plain white plastic one may come with it.
Rice should be mixed immediately after cooked, before served. This is to let excess amount of moisture to escape, and to make the grains of rice consistent throughout. A rice paddle comes in handy to do this job. While mixing rice, it is important not to mash the grains. Try to mix the rice as if you cut it using a shamoji.
Because Japanese rice is glutenous, grains tend to stick to a shamoji and it can be annoying. You can buy a non-stick shamoji, which has tiny ridges on the surface to prevent rice from sticking (the bottom one in the picture above). Alternatively you can dip a shamoji in water each time before using it.