Also known as: childhood—Jikumaru (竺丸)

Second son of Date Terumune and Yoshihime, Kojirou was favored by his mother over his older brother Date Masamune for succession as head of the Date Clan. However, Terumune favored Masamune, who became head of the Date Clan in 1584.

Yoshihime planned the assassination of Masamune, but after she failed to poison him in 1590, Masamune ordered Kojirou's death.