Born in 1619 into a family of acupuncturists in Kyoto. As a child he entered Hieizan and Myoshin-ji to study Zen, but then became the pupil of the Zhu Xi scholar Tani Jichu in Tosa and turned to Confucianism. In 1655 he returned to Kyoto and opened a private school. Known as a stern Zhu Xi scholar, he is said to have had as many as 6,000 disciples. Among his representative pupils were Asami Keisai, Sato Naokata, and Miyake Shosai — called the 'three heroes of the Kimon school' — who formed the 'Kimon school' or 'Ansai school,' holding fast to strict Zhu Xi dogmatism. In his later years, in 1665, he received the secret teachings of Shinto from Yoshikawa Koretari and founded 'Suika Shinto,' fusing Zhu Xi learning with Shinto. He developed a distinctive theological system that identified Amaterasu Omikami with the Confucian 'principle' (ri), becoming one of the sources of revere-the-emperor thought. He wrote 'Bunkai Hitsuroku,' 'Suikao Shinsetsu,' and other works. He died in 1682 at age 64.

Stern and passionate, a doctrinaire Zhu Xi scholar. He made no compromise even with his own disciples and enforced to the letter that 'one must not stray a single step from Zhu Xi.' On the other side, as an ardent seeker who went from Zen to Confucianism to Shinto, he also displayed an intellectual curiosity that never ceased. His disciples feared his anger 'like thunder' even as they revered him. Absolute confidence in his own views and pitiless criticism of others' are his hallmarks.

The Kimon school retained influence as an orthodox strand of Zhu Xi learning through the Edo period and became a source of revere-the-emperor thought. Suika Shinto came to be counted, together with Yoshida Shinto and Hakke Shinto, as one of the three great schools of Shinto, and exercised ideological influence on late-Tokugawa Mitogaku, kokugaku, and the Sonno Joi movement. After the Meiji Restoration, its view of the emperor as sacred was incorporated into a part of State Shinto. In current intellectual history research, the originality of its integration of Shinto and Confucianism is appraised, while its dogmatism and its influence on nationalism are also examined critically.