Zenzai is red bean soup made from beans called azuki.  It’s cooked and sweetened with sugar and with small balls of mochi added.  In mainland Japan it’s usually enjoyed during holiday seasons (wintertime) as a hot dessert.  In Okinawa Prefecture, the term “zenzai” commonly refers to the same bean soup served over shaved ice with “mochi” (enjoyed in the summertime). Other toppings, such as sweetened condensed milk, are occasionally added for flavor.