Cucumber rolls are called kappamaki in Japan. It is one of the most popular sushi rolls. The word kappa doesn’t actually mean cucumber in Japanese (that is Kyuubi); it refers to a demon or important figure from Japanese traditional folklore. The word kappa is a combination of words meaning “river” and “child” and is related to water. Somehow, a kappa is associated with cucumbers, hence the name of this sushi roll.