810 CE
Tea is brought to Japan by a Japanese Buddhist priest

Historians are not in complete agreement as to the identity of the individual who first brought tea to Japan. However, it is generally agreed that it was either Saicho in 805 CE or Eichu in 815 CE, who were both were Japanese Buddhist priests who are thought to have encountered tea in Chinese monasteries. While historians are not in agreement as to who first brought tea to Japan, it is clearly recorded in the Nippon Koko that Eichu presented tea to the Japanese Emperor Saga in 815 CE.

Source: Anderson, J. L. (1987). Japanese tea ritual: Religion in practice. Man, 475-498.