Oshi was originally established as a fief of 100,000 koku given to Ieyasu's fourth son, Tadayoshi MATSUDAIRA; however, as Tadayoshi was still a child, the fief was entrusted to Ietada until Tadayoshi came of age.
本来忍は家康の四男・松平忠吉が10万石で与えられたものだが、忠吉はまだ幼少のため、彼が成人するまでは家忠が預ったものである。