These mangoes calle "taiyo no tamago" which litterally translates to eggs of the sun, are types of mangoes that are a local specialty of Miyazaki Prefecture, located in the south of Japan on Kyushu island. What makes them special is their high sugar content which is indicated by a sweetness degree called "todo" (糖度). In English, this refers to the Brix measure of fruit sweetness. The higher the number, the sweeter the fruit is. From a level of around 10, the mango is considered sweet to most people. To be classified as an "egg of the sun", as they are called, the sweetness level must be above 15 (very sweet ones can even go up to level 20). Their shape must be perfect and the size must be exceptionally large.