Rice bowls. There are two sizes, small (5”diameter and 2” high ),and large, in Japan. We call the small one, “rice bowl / meshichawan” and serve just the rice, and refilled as wish. Bigger one is called “donburi”, and the rice often covered with the main dish, such as tempura, tonkatsu (pork cutlet), beef with some source, called tendon, katsudon, gyudon, respectively. Of course, for the bigger appetite, the donburi serves just white rice.
Japanese holds the rice bowl up in the air while eating, which is considered polite way to eat. When I was a kid, if I did not , I was yelled at “do not eat like a dog”. I know different culture has its own way of eating. Rice is the most important part of the Japanese culture. Rice served like the gold standard in Edo era (1603-1867). The local government was measured how much white rice in stocks, like we used to back up our currency with the gold.