He lost much of his influence and power upon Hidetada's death in 1632. Six years later, Doi became one of the first to be appointed to the newly created post of Tairō (Great Elder), and was made daimyō (feudal lord) of Koga Domain in Shimōsa Province, with a revenue of 160,000 koku.
After Hidetada's death in 1632, He lost much of his influence and power. Six years later, Doi was appointed as one of the first Tairōs (Great Elders) and became a daimyō (feudal lord) of Koga Domain in Shimōsa Province with an income of 160,000 koku.