Born into a farming family in Ishida village, Tama District, Musashi Province (present-day Hino, Tokyo). Orphaned in childhood, he studied swordsmanship while peddling the family's medicinal powder, Ishida Sanyaku. Meeting Kondo Isami, he joined the Tennen Rishin-ryu dojo at Shieikan and thereafter acted as Kondo's right hand. In 1863 he traveled to Kyoto with the Roshi-gumi militia, and when the Shinsengumi was formed, became its vice-commander. Earning the nickname "Demon Vice-Commander," he enforced a strict code of conduct — the Kyokuchu Hatto — ruthlessly purging deserters and rule-breakers to forge a tightly disciplined force. His operational planning before the Ikedaya Incident of 1864 helped make the Shinsengumi the most feared swordsmen of the late Edo period. After the shogunate's defeat at the Battle of Toba-Fushimi in 1868, he sailed north with Enomoto Takeaki to Ezo (Hokkaido) and continued to resist the new government forces from the stronghold of Goryokaku in Hakodate. On 11 May 1869, in the midst of the Battle of Hakodate, he was struck by a bullet near the Ippongi gate and died in action at age 35. His unswerving loyalty to the shogunate until the very end made him a symbol of bushido spirit in the Meiji era and beyond.

A complex figure who combined iron will and cold-blooded judgment with deep affection for his comrades and a refined aesthetic sensibility. Beneath his severity lay a literary side — he was fond of haiku and left death poems from the battlefield. An absolute loyalty to Kondo Isami and a fierce conviction to live and die as a samurai lay at the core of all his actions.

As the iconic figure of the Shinsengumi — the most formidable swordsmen of the late Edo period — he was celebrated as the model samurai from the Meiji era onward. His final stand in Hakodate has been depicted countless times in literature, film, manga, and video games as the tragic final chapter of the old shogunate forces, and he remains one of the most beloved figures in Japanese history.