This Japanese confection is made with agar (the jelling agent), sugar and azuki-bean paste. Other flavorings such as persimmons or chestnuts are also sometimes used. Yokan, which is sold in Asian markets, will keep indefinitely in the refrigerator.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.