Castella

is a type of Japanese sponge cake and is known for its sweet, moist brioche-style flavour and texture. It is based on cakes introduced to Japan by Portuguese merchants in the 16th century. It was then popularized in the city of Nagasaki, where it is considered a specialty. Despite its foreign origins, it is considered a kind of ''wagashi'', or traditional Japanese confectionery.

To suit the tastes of Japanese people, ''mizuame'' syrup was added to the sponge cake to make it more moist, and ''zarame'' (coarse sugar) was added to the bottom to give it a coarser texture. Castella is usually baked in square or rectangular molds, then cut and sold in long boxes, with the cake inside being approximately long. Provided by Wikipedia