Sembei(alternatively spelled as senbei) is one of the traditional crackers eaten in Japan. Other crakers are arare and okaki. Snacks which use rice flour as the main ingredients are called rice snack in Japan and sembei is usually recognized as rice cracker but there are several sembei which are based with other flours, such as wheat and starch flours.
Sembei are sold everywhere in Japan, mostly sold in plastic bags but there are sembei stores which grill and sell there sembei by pieces at there stores.
The most famous and the oldest existing sembei is Soka sembei. Soka sembei is produced in Soka, a city in eastern Saitama prefecture. Soka was the one of the post towns of Nikko kaido, one of the five routes of the Edo period.
Unfortunately Soka is not a popular tourist destination in Saitama as like Kawagoe, most of the Soka sembei are sold as gifts and also able to buy in stores in Tokyo too.