Jukujozuma: Karamitsuku yoru (2001)

Kyoko has been married to Yuji—who is younger than her—for three years, and the couple has now hit a slump in their relationship. Then one day, Yuji is told during a company health checkup that he might have diabetes. Kyoko worries after hearing from Etsuko, a neighbor, that diabetes can diminish a man's sexual potency. A few days later, Kyoko runs into Etsuko as she is heading out to film an adult video, and is stunned by the woman's high spirits. Meanwhile, Yuji—stretching his meager allowance—indulges in erotic fantasies about a glamour model while looking forward to Kyoko's upcoming birthday...