His domain was increased by 10,000 koku and moved to Koga Domain in Shimosa Province, with his promotion as roju (member of shogun's council of elders), but this was cut short by his death in the following year.
貞享2年（1685年）に信之は老中に栄進したことから1万石加増の上で下総国古河藩へ移されたが、翌年に死去した。