Yasunaga, a direct descendant of the Toda clan, who married Princess Matsu, the stepsister of Ieyasu TOKUGAWA from different mothers, and being adopted by his wife's family he went by the name as Yasunaga MATSUDAIRA; from then, over a number of generations the name of Matsudaira clan had been inherited.
戸田氏の嫡流は康長は徳川家康の異母妹　松姫の婿となり松平康長となり代々、松平姓を継承する。