Taiyaki （鯛焼き） 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, cheese, or sweet potato. Some shops even sell taiyaki with okonomiyaki, gyoza filling, or a sausage inside.
The dough that made from flour, suger, baking soda is poured into baking fish-shaped mold for each side. It put a red beans bean paste on one side. And then, bake together both sides.