Things you should know about Japanese Teas
All teas, wherever they are from around the world, come from the Camellia sinensis tea plant. What essentially puts the teas into their respective categories (green, white, oolong, black) is the oxidization process, which is what naturally happens when the picked leaves come into contact with oxygen.

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Green tea, which makes up over 90% of tea production in Japan, is a tea with 0% oxidation. How this is achieved is by steaming the tea leaves immediately after they are picked to prevent oxidation (steaming is the Japanese style green tea production. Chinese green teas are produced differently). The leaves are then tightly rolled during the drying process. This allows each leaf to retain its original flavor and natural green color.
Japanese green teas are further divided into two main sub-categories depending on the cultivation process: (a) tea grown under full sunlight, and (b) tea that is shade-cultivated.