In the Middle Ages in Japan, "samurai" is the title which is distinguished from common people. In the Edo era, there are four class distinctions, which are "samurais", "farmers", "artisans", "merchants". Among them, "samurai" is the highest class. They are allowed to have family name, belt on swords, and have other privileges. In various ways, they are distinguished from common people. Some people call them "mononofu" or "bushi" which means warriors, especially professional soldiers to their master. During peaceful time, they are often regarded as nuisances.