Taiyaki is a Japanese fish-shaped cake. The most common filling is red bean paste that is made from sweetened azuki beans. Other common fillings may be custard, chocolate, or cheese. Some shops even sell taiyaki with okonomiyaki, gyoza filling, or a sausage inside.
Taiyaki is made using regular pancake or waffle batter. The batter is poured into a fish-shaped mold for each side. The filling is then put on one side and the mold is closed. It is then cooked on both sides until golden brown.
Taiyaki was first baked by a sweet shop Naniwaya in Azabu, Tokyo in 1909, and now can be found all over Japan, especially at food courts of supermarkets and Japanese festivals.