Shiro-an (白あん) is a sweet Japanese white bean paste used in wagashi confections such as daifuku and nerikiri. Compare anko, which refers to the red bean paste made with the adzuki bean.
Shiro-an is difficult to acquire outside of Japan, as are the white beans called shiro ingen mame that are used to produce it. Lima Beans, white kidney beans, and navy beans are acceptable substitutes.