Nichiko (1532 - 1598) was a monk of Nichiren Sect in the Azuchi-momoyama period. His go (pen name) was Ryunin and Busshinin. His father was Tsunenobu DATE, a wealthy oil merchant in Sakai City.
He initially entered Chogen-ji Temple in Sakai and studied at Onjo-ji Temple (Mii-dera Temple) and Enryaku-ji Temple on Mt. Hiei. It is said that Sonkei, his mentor at Mt. Hiei, appreciated Nichiko's broad scholarship and presented him a fragment of Murasaki kesa (purple robe for Buddhist priest), which was in connection with Saicho and was a temple treasure. In 1555, he succeeded the position of the third chief priest of Choho-ji Temple in Kyoto. While he reconstructed Sakai Chogen-ji Temple in 1558, he also gained faith from Miyoshi clan in Kawachi Province. Although he originally adopted shakubuku shugi (the method of propagating Buddhism through correcting others' mistaken views), he later converted to Setsuju shugi (the method of propagating Buddhism through teaching without pointing out others' mistaken views) after a religious debate with Jodo Sect (so-called Azuchi Shuron) that was conducted in 1579 at the behest of Nobunaga ODA.