Fresh kuromame just popped out of the shell presents beautiful smooth and shiny appearance. The shape of the beans is an ordinary, slightly oblong bean-shape like the ones of fresh edamame green soybeans. But when it is dried, it becomes perfect round shape. This is magical to me. Here is teh kuromame recipe.
I cook the beans with my special egg shaped iron ball. When you do not have this special ball, you can use old nail, but please wrap it up in a cheese cloth, so that you can spot it and remove it without hurting yourself and your family after cooking the beans. The color of anthocyanin, when it contacts with iron, stabilized and produces appealing dark purple color.