Onna Jimuin: Shikijo Seikatsu (1982)
1982A librarian who is the mistress of of a married dude sleeps with a pregnant young woman and her lowlife boyfriend separately, and then she tries to break them apart.
Actors: Sabu Kawahara
Nurse Diary: Wicked Finger (1979)
1979A doctor has an exhibitionist married female patient who unnecessarily strips in front of him while he checks her up. When she does it again the second time, he screws her.
Captured Mother and Daughter: She Beast (1987)
1987A mother saves her daughter from her thug boyfriend, who is planning to make a prostitute out of her, and two of his clients/peers by letting them gangbang her.
The Eel (1997) aka Unagi
1997A husband comes home purposely early from his fishing trip to catch his wife screwing her lover.