Amagashi

May 4th on the lunar calendar is called yukkanufī (literally, “the fourth day”.) It was known as a special day for children because they could ask their parents to buy any toy they desired. In the old days, unlike mainland Japan, there was no custom of celebrating the Boy’s Festival on May 5 in Okinawa. Instead, yukkanufī became a day to give children toys, although its origins are unclear. The following day, parents would make amagashi as a treat for their children. Rolled oats and green beans (or azuki beans) were boiled with plenty of brown sugar and then eaten with the stem of an iris, a flower that is also a fixture of the Boy’s Festival in Japan. Perhaps Okinawan people celebrated both May 4th and 5th as the children’s festival. 

In the past, amagashi was made by boiling cracked barley, which was mixed with koji yeast and then left to rest overnight. It was quite sour, so people would add a little bit of sugar before eating it. Hence it used to be like amakasu¹, instead of amagashi (sweets.)
　The contemporary version of amagashi would be Okinawan zenzai.
　Okinawan zenzai uses cracked oats as its main ingredient, boiling them with azuki beans, red kidney beans, and brown sugar. Finally, a few rice flour dumplings are added before refrigerating. 
　Visiting the public market in Naha, I would often see an old lady pushing a cart loaded with huge tin cans of zenzai. I wasn’t sure whether or not it was safe, but I couldn’t resist ordering some. She would pour the zenzai into a styrofoam cup and hand it to me. The strong sweetness made me feel dizzy.

For me, that was zenzai. But recently I found out that there is a new type. Today, the most popular zenzai is called koori-zenzai. It is topped with plenty of shaved ice, similar to Japanese uji-kintoki, shaved ice topped with sweet red beans and rice flour dumplings.
　Near the schools in Okinawa you can find affordable restaurants and this zenzai is the most popular snack among students today. 
　It seems quite reasonable, as the shaved ice would take the edge off the sweetness, making it more moderate. Amagashi evolved into koori-zenzai. In that sense, food is always being renewed and improved.