"Kokura Miyamoto Kakei-zu," written during the late Edo period, explains Musashi's origin as "he was adopted into Muninosuke SHINMEN," therefore, some historians consider that Muni was Musashi's adoptive father.
また、江戸後期にまとめられた小倉宮本家系図の「新免無二之助の養子となる《為新免無二之助養子》」の記述を根拠に無二は養父であると主張する意見もある。