”Lucky Direction Roll." Thick uncut sushi roll eaten as seasonal food at Setsubun (Febr. 3). 恵方巻.
Other name is kaburizushi, ”Sushi where you bite off pieces" かぶり寿司 , (kaburu = kajiru, to bite off, gnaw, set your teeth into), pointing at the fact that these thick sushi rolls are uncut.
Ehomaki are traditionally from Osaka and people would take a bite off them while facing in the lucky direction of the year (i.e. the direction of the Zodiac animal) and making a silent wish.
The reason the rolls are not cut is in Japanese 「縁を切らない」- not to cut off good luck. And the reason it has to be a sushi roll (maki) is 「福を巻き込む」- to catch good fortune.
The ingredients of an Ehomaki are free as long as the whole is colorful; they also may include some things not normally used in sushi. Sometimes seven different colors are used to remind one of the Seven Deities of Good Fortune.
Ehomaki are today popular nationwide, but this has not always been the case. It is in fact a quite recent phenomenon, brought about by... convenience stores. Seven Eleven and other convenience stores started selling and promoting Ehomaki from the mid-nineties on and they were so successful that now everyone knows them and more than half of all Japanese set their teeth in Ehomaki at Setsubun (or even several weeks before that date). Seven Eleven alone sold 5.2 million rolls in 2011.