Another theory states that the Abura-no-koji Incident, in which the Shinsen-gumi masterless warrior party assassinated ITO, had occurred based on the information given at the time SAITO returned.
新選組が伊東を暗殺した油小路事件は、斎藤が復帰の際にもたらした情報に基づいて起きたという説もある。