Hell's Revenge(1979)

Kenzo, Azusa's husband, has a heart condition but his passion for sex has not diminished one iota from the time he was a virile young man. Azusa does not refuse her husband for he is very wealthy and if he should happen to die of excess sex she would inherit a vast fortune. If only Azusa could kill him without staining her own hands. Unable to do it alone, she asks the aid of Naoya who is only too glad to help.