Koshiro had three sons and a daughter. His sons would then become respectively Ichikawa Danjuro XI, Matsumoto Hakuo I (known once as Koshiro VIII) and Onoe Shoroku II. He passed Danjuro IX's knowledge and teaching techniques to them. They became without any doubts the best tachiyaku (male role specialists) of the first and early second half of the 20th century. His daughter married the "onnagata" actor Nakamura Jakuemon IV. He was also the father-in-law of Nakamura Kichiemon I's daughter. His grandsons became the most famous actors of the second half of the 20th century and still perform alongside his great-grandsons. Today he has blood relatives in many other Kabuki clans, such as Onoe Kikugoro, Danjuro and indirectly with Nakamura Kanzaburo's clans. No other actor left such a wide inheritance in the kabuki world.