Kien's father was Nariyoshi MINAGAWA (who was also called Shundo and Hakushu), and his biological younger brother was Nariakira FUJITANI (who was also called Sojo and Kitanobe) who was known as a scholar of ancient Japanese thought and culture ('Kokugakusha' in Japanese).
父は皆川成慶（春洞、白洲）で、実弟に国学者富士谷成章（層城、北辺）がいる。