Sessai aided his nephew in consolidating the Imagawa territories, and in a number of political maneuvers which gained Imagawa influence over the Matsudaira family.
However, Yoshimoto soon came into conflict with the Oda clan, and faced defeat at the 1542 battle of Azukizaka.
In 1552–1554, Imagawa secured a treaty and alliance between his family and those of the Hōjō and Takeda Shingen.
At some point after this, Sessai began to advise Matsudaira Motoyasu, though the extent of his role in Tokugawa's military exploits is unclear, and unlikely to be great.
You can help Wikipedia by expanding it.This biography of a Japanese religious figure is a stub.