His father Masayuki's two older brothers died at that time, so Masayuki succeeded the Sanada family; thus Nobushige left Kofuchu (Kofu City) and moved to Joshu (Iwabitsu-jo Castle), following his father.
この際、父・昌幸の2人の兄も亡くなったため、真田家は昌幸が継ぐこととなり、信繁は父に付き従い古府中（甲府市）を離れ上州（岩櫃城）に移る。