The history of tea in Japan has its earliest known references in a text written by a Buddhist monk in the 9th century. Tea became a drink of the religious classes in Japan when Japanese priests and envoys sent to China to learn about its culture brought tea to Japan. The first form of tea brought from China was probably brick tea (磚茶 tancha?). Ancient recordings indicate the first batch of tea seeds were brought by a priest named Saicho in 805 and then by another named Kukai in 806. It became a drink of the royal classes when Emperor Saga, the Japanese emperor, encouraged the growth of tea plants. Seeds were imported from China, and cultivation in Japan began.
In 1191, the famous Zen priest Eisai (1141–1215) brought back tea seeds to Kyoto. Some of the seeds given to the priest Myoe Shonin became the basis for Uji tea. The oldest tea specialty book in Japan, Kissa Yōjōki (喫茶養生記 "How to Stay Healthy by Drinking Tea") was written by Eisai. The two-volume book was written in 1211 after his second and last visit to China. The first sentence states, "Tea is the ultimate mental and medical remedy and has the ability to make one's life more full and complete". The preface describes how drinking tea can have a positive effect on the five vital organs, especially the heart. It discusses tea's medicinal qualities, which include easing the effects of alcohol, acting as a stimulant, curing blotchiness, quenching thirst, eliminating indigestion, curing beriberi disease, preventing fatigue, and improving urinary and brain function. Part One also explains the shapes of tea plants, tea flowers and tea leaves and covers how to grow tea plants and process tea leaves. Part Two discusses the specific dosage and method required for individual physical ailments.