Born the son of a Fukui domain retainer, he wrote "Keihatsuroku" (Record of Self-Awakening) at fifteen — a text still read today as a classic of Japanese youth education. He studied medicine and Dutch learning under Ogata Koan at the Tekijuku academy, and also attended the Shoheizaka school in Edo. Recognized by Matsudaira Shungaku as talented, he served as the domain's political advisor and worked energetically to negotiate with other domains in support of Hitotsubashi Yoshinobu. He was arrested with Yoshida Shoin and others during the Ansei Purge (1858-1859) and executed at Edo Tenma-cho in 1859, aged just twenty-six. "Keihatsuroku" contains five personal admonishments — "Remove childish thinking, strive in study, choose friends well, deepen benevolence, know shame" — and remains widely read today as a masterwork of self-awakening.

Young yet possessed of high ambition and clear intelligence, he disciplined himself rigorously. Matsudaira Shungaku called him "the first man in all the realm." He combined passionate patriotism with cool diplomatic sense.

"Keihatsuroku" is still widely read as one of Japan's earliest works of personal development. As a brilliant young talent cut down in the Ansei Purge, he is especially mourned among the loyalists of the Bakumatsu era.