In 1587, at the time of Hideyoshi's expedition in Kyushu, went to Hakozaki
(Chikuzen), was presented to him and was confirmed in his possession of Tsushima.
In 1590 he was sent on a mission to Korea to oblige the king of that country
to resume the periodical embassies that seemed to have fallen into neglect. He
was successful, but this did not prevent the war, which the Taiko had already
resolved upon. Yoshitomo took part in it under the command of his father
Konishi Yukinaga. In 1600 he sided with Ieyasu, but remained in Tsushima and
was not present at the battle of Sekigahara. The same year he was again sent
to Korea to conclude peace, and on his return his revenue were increased to
100,000 koku.
Yoshitomo had been baptized in 1591, but the fear of displeasing Ieyasu
caused him to abandon his faith.