Yokan is a Japanese traditional thick jellied dessert, a thick, jellied Japanese dessert made from agar and sugar. Then, usually the main ingredient is red bean paste but there are many types of yokan which use other vegetables or fruits instead of red bean.
It can be kept at room temperature and it can be kept for a long period. Therefore it can be used as emergency ration or energy bar for sport activity. There is also less firm type yokan called Mizu-yokan which mostly eaten in summer and kept in fridge before consuming.
Yokan is usually sold as bars in stores but usually been sliced in 1 cm wide when served. Then, it is hard to find at restaurants or tea houses. The word Yokan came from China and it actually means sheep soup and looked like a aspic. It is told that Japanese monks who do not eat meat changed the ingredient from sheep meat to red bean.