Traditional Taiyaki Maker, Taiyaki is a Japanese fish-shaped cake. It imitates the shape of the tai (Japanese red seabream), which it is named after. 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.