 Late in 1841, on the death of his foster-father (brother-in-law) he became "daimyō" of Sendai Domain, received the courtesy titles of "Mutsu no Kami" and "Sakon-e gon-shosho".He also changed his name to Date Yoshikuni at this time, taking the "kuni" character from his predecessor's name.Despite its high "kokudaka" of 620,000 "koku," the domain inherited by Date Yoshikuni was beset with problems.