Uwakizuma: Ura nama nozoki(2002)

Ryoko's husband is an international airline pilot. Taking advantage of his frequent absences, she busily engages in extramarital affairs. One of her lovers is Naoya, the husband of her close neighbor and fellow housewife, Saori. When Saori discovers the affair, she fiercely confronts Ryoko; shortly thereafter, Saori falls to her death from a building.