Yokan is a Japanese dessert that is made of bean paste (typically adzuki or white kidney beans), agar, and sugar. We received this yokan as a gift and it was delicious! This yokan is made of matcha and shiroan (white kidney bean paste). I personally prefer yokan made out of shiroan compared to adzuki. In New York you can find yokan at Japanese supermarkets like Sunrise Supermarket (41st Street btw. 5th + Madison) or for a higher quality yokan you can go to Minamoto Kitchoan which is located near Rockefeller Center.
However the one that we had was Toraya Yokan which is very famous and high reputation. If you are ever in Japan please visit one of their shops: Toraya Website
They also have some locations in California!