The Japanese sweet red bean paste is called anko. It is made primarily from azuki beans that are boiled, mashed, and sweetened with sugar. In Japanese, “an” can refer broadly to a sweet paste, while “anko” commonly means sweet azuki-bean paste.
Japanese confectionery uses several textures of anko. Tsubuan retains pieces of bean, tsubushian is partly mashed, and koshian is passed through a sieve to create a smooth paste without bean skins. Koshian is especially common in traditional sweets.
Anko fills or accompanies many wagashi, including daifuku, dorayaki, manju, taiyaki, and anpan. It also appears in desserts such as anmitsu and oshiruko. A common mix-up is confusing anko with the entire dessert: daifuku is mochi filled with anko, while anko is the filling itself. Although red azuki paste is the standard meaning, Japanese cuisine also has white-bean, green-bean, and chestnut pastes.