Nichijo (1298 - August 8, 1369) was a priest of the Nichiren/Hokke sect who lived during the period of Northern and Southern Courts (Japan). It is said that his father was Yorishige UESUGI, a descendant of the Northern House of the Fujiwara clan, and his mother was a daughter of the Ashikaga clan, and he was the uncle of Takauji ASHIKAGA, seii taishogun (literally, "great general who subdues the barbarians"). His azana (adult males nickname)was Horyu. His go (pen name) was Myoryuin. He was born in Suruga Province (current Shizuoka Prefecture). He was the founder of Rokujo monryu (the Rokujo Lineage) of the Nichiren sect.
First, he studied under Nichii, jibuko (Minister of the Ministry of Civil Administration) (Hongaku-ji Temple [Shizuoka City], Suruga Province), and then under Makaichibo Nichiin, a distinguished priest who outdebated all sects according to the 'Kamakura denchu mondo' (Dialogue in the Palace of Kamakura bakufu [Japanese feudal government headed by a shogun]); Nichiin passed down the Honsho-ji Temple in Kamakura, Sagami Province and the Honjo-ji Temple in Sanjo, Echigo Province to Nichijo. In his 'Kamakura denchu mondo,' he described how his mentor Nichiin won the debate when arguing against all sects in the inside of the palace of Kamakura bakufu (the Seii taishogun of the time was Imperial Prince Morikuni, and the regent was Takatoki HOJO). When he went to the capital in 1338, he moved Honsho-ji Temple in Kamakura to Rokujo Horikawa, Kyoto, and renamed it as Honkoku-ji Temple (written as 本国寺, written today as 本圀寺). Nichijo's pupil Nichiden was passed down the Honkoku-ji Temple in Kyoto, and Nichijin (the founder of Jinmon lineage of Hokke sect; a lineage of Honzen-ji Temple) was passed down the Honjo-ji Temple in Sanjo, Echigo Province. The lineage of Honkoku-ji Temple was called Rokujo monryu (the Rokujo lineage); it formed the two major lineages of the Nichiren sect in Kyoto along with the Shijo monryu (the Shijo lineage) of Myoken-ji Temple, which was founded by Nichizo.