Cure (1997)

Cure is a 1997 Japanese horror/thriller directed by Kiyoshi Kurosawa (who also directed Pulse). A series of identical murders are committed, each by a different person who is found nearby afterwards remembering killing and mutilating the victim but not why. The chief investigator has a wife who is mentally unstable, and he (in concert with a psychologist) uses what he has learned about mental illness to try to figure out the murders. The most interesting part takes place after he figures it out and a subject of interest is committed to a psychiatric hospital for observation. This one sneaks up on you.

trailer:

Images Journal calls it a "minor masterpiece" and says,

Much of the film's subtle power and resonance is predicated on its serpentine narrative ambiguities, unanswerable character motivations, and dramatic incidents. This would be understandably maddening in lesser hands, but Kurosawa's direction is always assured and the film's deviousness is always sufficiently grounded by its purposeful storyline and magnificent performances. Although the film will nevertheless drive viewers bonkers who demand straight lines where they don't exist, Cure will be a welcome reward for those adventurous souls who like their lines on the squiggly side.

Moria finds it confusing. HorrorNews.net says it " manages to be equal parts detective story, horror film and psychological thriller with an evenhandedness rarely seen." Combustible Celluloid gives it 3 1/2 out of 4 stars and calls it "a mesmerizing film." Rotten Tomatoes has a critics rating of 91%.