Incidentally, the Mitsui family originally came from Matsuzaka City in the former Ise Province, which was a feudal domain of the Kii clan, and hence they had strong ties with the house of Kishu-Tokugawa.
ちなみに三井家は紀州藩領であった伊勢国松阪市が一族のルーツであり、それが縁で紀州徳川家とは強いつながりがあった。