Saori -Bishoujo-tachi no Yakata-

Saori witnesses sexual intercourse in a park, which inspires her masturbating at home. Later, she dreams she is abducted by two men and sees illusions while being confined in a mansion by a female owner.

In the dream, she sees many immoral sexual acts: father-daughter incest, brother-sister incest, sisters' incest in a shinto shrine, female teacher and male student in a classroom, female senior and male junior in a University, male boss and female office worker, and police man and police woman.

[from Wikipedia]