A showcase for Ken Watanabe

If moviegoers didn’t exactly show an appetite for the second Truman Capote biopic within a year (the box-office gross of “Capote� was 25 times that of the straggling “Infamous�), it’s hard to imagine they’ll have much use for a second Alzheimer’s weepie within a month.

Charting its protagonist’s agonizing slide into senility, the Japanese melodrama “Memories of Tomorrow� invites mostly unflattering comparisons with “Away From Her,� the directorial debut of Canadian actress Sarah Polley (currently in theaters). Though Polley’s film, adapted from an Alice Munro short story, is notable for its quiet perceptiveness, “Memories of Tomorrow,� also an adaptation (of a novel by Hiroshi Ogiwara), traffics for the most part in disease-of-the-week cliches.

At 49, Saeki (Ken Watanabe) is a driven advertising executive who has long prioritized work over family life. He takes his wife, Emiko (Kanako Higuchi), for granted and has a testy relationship with daughter Rie (Kazue Fukiishi).

The first symptoms are some irksome memory lapses. Normally all-business and ultraefficient, Saeki forgets meetings, misses highway exits, can’t remember who starred in “Titanic.� The devastating diagnosis -- early-onset Alzheimer’s disease -- sends him into a fit of rage, then a depressive tailspin.

The movie appears to have been conceived mainly as a showcase for Watanabe, who optioned the rights to the source novel and served as executive producer. He gets to do far more here than in his generally constricting Hollywood roles (“Letters From Iwo Jima,� “Memoirs of a Geisha�), in a performance that ranges from flashy Oscar-clip emoting to quieter moments of desolation (he won best actor at the awards of the Japanese academy).

In a less showy role, Higuchi breathes life into the stock character of the long-suffering wife: Emiko experiences his decline as an abandonment but, amid her grief, finds independence for the first time, in middle age.

But the script’s subtler nuances are too often drowned out by awkward histrionics. The lovely bits of actorly restraint are also ill-served by director Yukihiko Tsutsumi’s distracting flourishes: subjective camerawork to evoke Saeki’s disorientation, unbearably maudlin strings on the soundtrack. In his more subdued moments, though, Watanabe cuts through the clutter.

“Memories of Tomorrow.� Not rated. In Japanese with English subtitles. Running time: 2 hours, 2 minutes. Exclusively at Laemmle’s Music Hall, 9036 Wilshire Blvd., Beverly Hills, (310) 274-6869.