Sanada clan
In 1574, his father Yukitaka died. At that point, his eldest brother Sanada Nobutsuna had already succeeded his father as the head of the Sanada clan. However, during the disastrous Battle of Nagashino (1575) against the Oda clan, both his older brothers, Nobutsuna and Masateru, were killed, so he came back to Sanada clan and claimed his inheritance. In this, Masayuki supposedly had the support of Kōsaka Masanobu, who held Kaizu Castle in Northern Shinano and was also a chief retainer of the Takeda clan. Katsuyori accepted his claim without any qualms.