Ichitaro's allegiance to Shozo MAKINO never swayed throughout Makino's career, working with Makino when the latter was employed by Yokota Shokai, and staying with Makino after Yokota Shokai was merged in 1912 to form Nikkatsu Corporation; Ichitaro followed Makino when he established the Mikado Shokai film studio to win his independence from Nikkatsu Corporation in 1919, and followed him back when he subsequently returned to Nikkatsu Corporation.
横田商会、1912年（大正元年）の同社の合併による日活の設立、1919年（大正8年）の牧野の日活からの独立によるミカド商会の設立、そして牧野の日活への復帰、と牧野省三の行動に、市太郎は完全に同行する。