In 1582, the death of Oda Nobunaga in the Incident at Honnōji left Kai and Shinano Provinces without an overlord, and the struggle between Ieyasu and Hōjō Ujinao began.
However, at that time, the two had nearly equal strength, and thinking that a serious war would weaken even the winner, they sought peace.
As part of the accord, Ieyasu agreed to give Toku to Ujinao to be his wife.
In 1594, Hideyoshi arranged for Toku to marry Ikeda Terumasa.
Tadatsugu became the lord of Okayama Castle at age five, following the death of Kobayakawa Hideaki.