I love tea and drink many cups of Jasmine tea every day. Interestingly the ninja in the 1600s had the same feeling. The used tea as a tool for many purposes and gathered leaves and carried them on their person.
Ninja used to carry around a canteen of green tea from which they would also make a poison. They did this by burying the canteen for around a month then mixing soya bean paste (miso) into the tea.
It was the practice to mix green tea and miso to make a medicine, but when giving the Ninja version it would poison you.
This poison was called Gyokuro in Ninja parlance and is also the name of classic shade grown or hidden Japanese tea of fine quality.
Gyokuro grade tea is the finest grade of the leaf of Camellia sinensis. Its Japanese name can be translated as “precious dew”. Gyokuro is cultivated and harvested in a manner that greatly reduces its bitterness. (The leaves are protected from the sun by bamboo mats, concentrating many of the phytochemicals in the leaves)
The primary reason for Gyokuro’s brothy non-bitter taste is it’s exceptionally high content of L-thiamine, an amino acid that prevents bitterness. L-thiamine has another benefit: this amino acid stimulates alpha brain waves, creating a deep state of relaxation and simultaneous mental alertness similar to that achieved in meditation. L-thiamine has also been shown to improve hypertension, enhance learning performance, heighten mental acuity, promote concentration, support the immune system, and reduce the addictive effects of caffeine.
One of the most renowned tea gardens for growing Gyokuro is Kyoto which is a significant region in Ninja history being the home to Ninja families and schools.
Tea grown from this region has most likely been used as a poison and stimulate by Ninjas over the centuries.
To stay awake
It would seem to be a tradition of making “Shinobi tea” which is a cold green tea, in modern times made also with ice. I guess this is because Ninja couldn’t start fires and would drink their tea cold. Cold tea takes longer to brew so carrying a canteen of cold tea around makes sense as brewing vessel as well as a container.
Tea harvest and attack
With the new tea crop being harvested in late May and early June in Japan, one learns that people tend to enjoy more of the stimulating drink and thus have a tendency to stay up later because of increased caffeine intake. Early evening would not be the optimum time for a ninja because the occupants would be awake and alert.
A special tea used by shinobi, originating from the island of Mauritius it was first brewed by a small family of ninja butlers to help ease the pains of ninja-constipation. Ninja Tea is mentioned in the 2nd verse of the Mauritian National Anthem. Perhaps this is due to the many hours and ninja would have to spend sitting still in wait during his missions.