Nichien (year of birth and death unknown) was a priest of the Tendai sect in the mid Heian period. He was originally from Hizen Province. He was a disciple of Gon no Risshi (a provisional rank in the lowest managerial position) Ninkan.
Responding to a request by a temple in Mt. Tendai, China for Enryaku-ji Temple to send a hand-written copy of Tendai Kyoshaku (doctrine book) which had been dispersed and lost in China, he went across the sea to Goetsu (Wuyue) as Soshi (delivering envoy) in 953. He was presented with a purple canonical robe by the King of Wu-yueh (銭俶), specially permitted to learn at Shitendai (an astronomical observatory) and returned to Japan in 957 with approximately 1,000 Buddhist and secular books and a Futenreki (the Futian calendar table) of Shin rekiho (a new method of making calendars) which had not been introduced to Japan. Emperor Murakami intended to present an imperial letter of Sogo (Office of Monastic Affairs) to praise his achievements but Nichien declined, going down to Dazaifu in Kyushu and erecting the Oura-dera Temple for FUJIWARA no Morosuke during the Koho era (964-968). With the introduction of the Futenreki, the Sukuyodo (a type of astrology) was established in Japan. Nichien seems to have been known for his activities in the field of Rokumei, rather than Suiyodo, however, as in "Nichureki" (Dual History), he was described not as a Sukuyoshi (master of an astrology based on the Sutra of constellations and planets) but as a Rokumeishi (teller of one's destiny) and well informed about Rokumei (one's lot) which tells fortunes by examining one's physiognomy or date of birth.