Gyokuro is the one of the highest quality tea leaves. The farmers are fully select old and excellent tea trees. They monitor the fertilization, cultivation of the tea trees and adapt to changing conditions daily. 20 days before they pick the leaves, they cover the field of Gyokuro with black screens made of a ditch reed or rush which block the Sun's rays. Then the leaves are picked, steamed and rolled on the same day to ensure their freshness. Gyokuro contain more Amino Acid ( a kind of pigment ) compared with Sencha tealeaves, while it contain less Tannic Acid and other substances that taste rough and sharp. Consequently Gyokuro tea looks bright green and tastes uniquely sweet. The unique taste of Gyokuro and Sencha is often compared to man and woman. The taste of Sencha is generally pictured as being strong man while the one of Gyokuro is like a kind woman. The total yield of Gyokuro tealeaves is limited, because it requires intensive labor to cover a vast field of tealeaves with the screens and pick the young buds of Gyokuro by hand.