The founder of the Rinzai school of Japanese zen. Born into a temple family, Eisai originally entered the Tendai sect and lived at the Miidera. However, the violent factionalism of the Tendai school at that time repulsed him, and he travelled from place to place seeking teaching. In 1168 he went to China to visit the famous sites of the T'ien-t'ai school (Tendai's Chinese root). He arrived at a time when Ch'an was dominant, and was very excited by its vibrance and novelty. He had no time for formal training, however, since he returned to Japan after only six months. After his return, he continued to serve the Tendai school. Eighteen years later, he returned to China once again, this time staying for four years and studying Ch'an intensively with masters of the Lin-chi school in various temples. He had an enlightenment experience, and returned to Japan in 1191 with the robes and certifications of a Ch'an master. After this, he worked to establish places that would be devoted solely to the study and practice of Ch'an. It is not clear that he wished to found a new school; in fact, he criticized his contemporary Dainichibō Nōnin for wanting to do just that. He remained a Tendai monk for the rest of his life and worked at many other projects as well, but it is clear that he at least wanted Zen practice to have a place of its own within the overall framework of Japanese Buddhism.
Despite the difficulties imposed by the jealousy of the Tendai establishment, Eisai gained increasing patronage among the aristocracy and rising military class, who were attracted by the vigour and action-orientation of his southern Sung-style Zen, as well has by his presentation of Zen as a practice that would help to protect the nation. In 1202 he was granted abbotship of the Kennin-ji, a temple in a government-controlled district of Kyoto. There he continued to teach Zen even while the court kept him busy overseeing building and restoration projects and performing Tendai-style esoteric rituals. He died in 1215, without having enjoyed any discernible success in establishing a self-standing Zen institution, and it fell to his spiritual descendants to set up Rinzai as an independent school. Nevertheless, he is honoured as the first transmitter of Rinzai Zen to Japan and the de jure founder of the school.