The romantic combination of an older woman and a younger man is common now in Hollywood films, which have come a long way since the day when a young (actually 30-year-old) Dustin Hoffman threw over a middle-age (actually 36-year-old) Anne Bancroft in "The Graduate." As film critic Roger Ebert astutely remarked, Bancroft's Mrs. Robinson was "the most sympathetic and intelligent" character in the film, while Hoffman's "insufferable creep" Benjamin didn't know what he was passing up.
This combination, however, is not often found in Japanese films. One reason, I suppose, is that women over a certain age — traditionally 25 — have long been, unfairly, considered past their romantic sell-by date, especially to younger guys, who might regard them as an onesan (older sister) or obasan (older woman) but rarely a potential kanojo (girlfriend). This is changing, though, as Nami Iguchi's "Hito no Sex o Warau na (Sex is no Laughing Matter)" makes refreshingly clear.
Based on an eponymous novel by Naokora Yamazaki, the film is an unusual combination of drama and comedy within a relationship, and it is shot in the by-now standard style for Japanese indies: longish cuts, no close-ups, and naturalistic dialogue and acting. Expecting, from the stylistics, an elliptical, subdued and downbeat look at age-inappropriate love, I was pleasantly surprised by the film's sly humor, freeform eroticism and blithe refusal to treat its theme as inherently sad.