The Emperor of Japanese Green Teas

Gyokuro is rolled form of shaded Japanese green tea leaf. What makes the Gyokuro tea leaf unique is that, for the final month before harvesting it is covered by shade. This shade prevents most of the L-Theanine, an amino acid, from converting into Catechins, the polyphenols responsible for most of the bitterness in lower-quality teas. As a result, Gyokuro tea has a sweet, unique taste that is very favorably compared to the sun-grown Sencha grade of teas.

L-Theanine is the so-called “Feel-good” Amino acid, and is primarily found in the leaves of the tea plant (C.Sinensis). While all teas have some L-Theanine, the largest quantities are found in the Gyokuro and Matcha teas. L-Theanine not only gives these teas their signature sweetness, but it also relaxes the body and mind. This comes from L-Theanine’s stimulation of the alpha brain waves, which produce a calming effect. 
L-Theanine, combined with caffeine, melts away stress and anxiety, and allows one to focus on the present task. This unique ability was praised by the Zen Buddhist monks, who popularized the use of tea in their meditation sessions