Yôichi Sai - Kuroi doresu no onna AKA Woman In A Black Dress (1987)

ThemovieDB description:
A woman named Fujiki Asuka arrives as an acquaintance of a sister in law for a day under the bar master Tamura who had guided Yakuza’s escaping as a shoji. Tamura who lives on the second floor of the store for the time being the son who wants to work here. A few days later, Tamura finds a handgun from Yuko’s baggage and holds a suspicion ….