Generally, Ryozo has been famous for participating in the Ikedaya Incident, and although it is unclear when he joined the Shinsengumi, yet he participated in the Palace Coup of August 18 which occurred on September 30, 1863, thus making it possible to infer that he had been a member since the time of the Miburoshigumi which was the forerunner of the Shinsengumi.
一般的には池田屋事件に参戦した隊士として有名で、入隊時期に関しては、正確には不明なものの、文久3年（1863年9月30日）に起きた八月十八日の政変に参加している事から、それ以前、つまり、新選組の前身・壬生浪士組の頃からの隊士である。