You can find them in most grocery shops or convenience stores in Japan, these round double pancake with a filling type of confectionery. They are called dorayaki, and the outsides are not exactly pancakes but spongy cakes based on the Castella recipe, which was brought by the Portugese to Japan in the 16th century. As a result the outside of the dorayaki is very soft.
Similar to the daifuku, dorayaki can also be had with a large variety of fillings, for example custard, jam or whipcream. But the most seen filling is anko which is a sweet bean paste. Eating such a sweet bean paste filled dorayaki together with icecream is a delicious combination.
A marking on the cakes is common to identify the bakery or area that the dorayaki is made. Therefore dorayaki are also popular souvenirs in some areas of Japan.
It is said that in the Edo period, there was only one outside layer which was folded on the edges to make a square with the filling exposed in the center.