Akisake yamaduke kamakura jyukusei (Matured salmon pickled in salt) is made using large buna salmon caught in autumn in the waters around Hakodate in Hokkaido, which are pickled in salt through a method called yamaduke for about 10 days. Buna salmon are considered low value, due to the brown color of their body, which resembles the color of beech trees and their leaves, as well as for being low in fat in comparison to red or silver salmons. However, buna salmon is an abundant source of protein, which is broken down into amino acid, the source of the umami flavor, by carefully maturing them inside a kamakura (snow-made house) at a temperature of around 0ºC for approximately three months. The salmon, which were matured slowly over a long period of time, become rich in unique flavors and nutrition that match perfectly with rice balls, fried rice or ochazuke (rice with tea poured over it). They are also recommended as snacks to accompany beverages such as sake and wine. The wisdom of making a little extra effort to create delicious preserved food is a technology Japan has to offer to the world.