After the Ikedaya Incident of July 8, 1864, where he was involved in the killings of several members of the anti-Shogunate faction, he collapsed after coughing up blood from tuberculosis (according to many theories) but based on his subsequent involvement in the Shinsengumi, it is unreasonable to think that he developed lung tuberculosis on that day.
元治元年（1864年）6月5日(旧暦)の池田屋事件で、討幕派数人を切り伏せ活躍したものの、直後に肺結核により喀血して倒れる（諸説あり）とされていたが、その後の新選組史において依然として活躍していることから、この日に肺結核が発症したとは考えにくい。