Castella (カステラ, Kasutera) is a popular Japanese sponge cake made of sugar, flour, eggs, and starch syrup, although its origins are found in Castilla ( In modern-day Spain).Now a specialty of Nagasaki, the cake was brought to Japan by Portuguese merchants in the 16th century. The name is derived from Portuguese Pão de Castela, meaning "bread from Castile". Castella cake is usually sold in long boxes, with the cake inside being approximately 27 cm long.