However, as Tadasuke's legitimate child Tadakane OKUBO prematurely died, Tadasuke tried to adopt his younger brother Tadataka to let him inherit the family headship.
だが忠佐の嫡子・大久保忠兼が早世してしまったため、弟の忠教を養子として迎えて後を継がせようとしていた。