The ninth lord of Mito Domain. As the spiritual pillar of the Sonno Joi (Revere the Emperor, Expel the Barbarians) movement, he exerted enormous influence on Bakumatsu politics. He founded the Kodokan institute to cultivate talent in both letters and martial arts, contributing to the development of Mito school thought. He was the father of Hitotsubashi Yoshinobu, who later became shogun. After Perry's arrival he advocated strongly for expulsion, and in the shogunal succession dispute backed the Hitotsubashi faction, clashing fiercely with Ii Naosuke and being ordered into house arrest during the Ansei Purge. He died the same year as the Sakuradamon incident. That his son Yoshinobu became the last shogun and returned power to the emperor might be considered one form of the "Sonno" ideal Nariaki had dreamed of. The Kodokan (now a nationally designated special historic site) survives in Mito City, conveying Nariaki's passion for education.

A reform-minded daimyo with intense conviction and drive. His expulsion beliefs were sometimes too rigid, but his passion for education and care for the people were genuine. He was also a father who never stopped placing hopes in his son Yoshinobu.

Through the development of Mito school thought and the founding of the Kodokan, he built the theoretical foundation of the Bakumatsu Sonno Joi movement. Ironically, when his son Yoshinobu returned power to the emperor, Nariaki's loyalist ideals were realized in the form of the Meiji Restoration.