What is the nagasaki castella sponge cake also know as?

Nagasaki castella sponge cake is also known as "Kasutera." This traditional Japanese cake has its origins in the 16th century, introduced by Portuguese missionaries. Made with simple ingredients like flour, sugar, eggs, and starch syrup, it is known for its moist texture and sweet flavor. Castella is popular in Japan and is often enjoyed as a snack or dessert.