According to some books, the reason why TAKECHI treated Izo coldly in his later years was, for example, from the discriminative feeling for Izo who had low social standing and no education compared with the other comrades, a sense of danger that exposure of many of the assassinations that Izo took part in may have unfavorable effects to his fellow comrades, and resentment and anxiety toward Izo for not taking his own life although those exposures could be prevented if he had committed suicide; furthermore, even if he had been a member of the Tosa kinnoto that aimed for "Sonno Joi (19th century slogan advocating reverence for the Emperor and the expulsion of foreigners) and overthrowing the Shogunate", he became a bodyguard to Kaishu KATSU (to be explained later) who was "a member of the open country wing and a vassal of the shogun"; Izo was disdained, for "although skillful in swordplay, he was a man with no resolute ideas and beliefs."
以蔵が晩年、武市らから冷遇されていた理由について諸書の記述によれば、他の同志より身分が低く教養が無いことによる差別的感情、彼が手がけた数々の暗殺が露見することにより他の同志に累が及ぶ危機感、彼が自刃してしまえばその露見が防げるにも拘らず彼自身がそれを行わなかったことに対する焦燥感や怒り、さらに“尊王攘夷・倒幕”を旨とする土佐勤王党に属しながら“開国派・幕臣”の勝海舟らの護衛を行うなどした（後述）ことにより“剣術こそ強いが確固たる思想・信念を持たぬ者”として軽蔑されたこと、などが原因ではないかと考えられている。