Through the kind intercession of Yoshiharu HORIO, Tomoharu was able to have an audience with Ieyasu TOKUGAWA in 1598, and worked for a time under Hideyasu YUKI.
その後、堀尾吉晴の斡旋で慶長3年（1598年）に徳川家康に拝謁し、一時結城秀康に仕える。