Eisai Zenji (1141-1215) was the head abbot of Kozan-ji. He brought back from china tea leaves, utensils and procedure for making the. When he founded this own temple the temple rules included rules about tea. He is the japanese founder of the Rinzai School of Zen.
He wrote the book Preservation of health through Drinking Tea (Kissa Youjouki). He administrated Matcha to the powerful Minamoto shogun for relief of his frequent hangovers.