Any time one of a character's introductory scenes consists of bad eating-acting you have the most simplistic of character definitions: the character is an idiot, with a bad moon rising. Both the family man and the stranger are introduced this way. They both turn out bad. No surprise. The first act of this film is full of bad indie nonsense, but after the lame setup material is out of the way, including Asano's snorefest of a background story speech that sets things in motion, the film finds it rhythm. And it's frighteningly good. And only then does it become unpredictable. There's a character swap about halfway through, and trying to figure out the relationship and motivations really put me on edge. The second half of the film is walking on razor blades.
Asano has pretty much jumped the shark, imo. He's played this character a hundred times. I don't think he does anything special here, but he's not bad. Kanji Furutachi is a good creep. In the first act he tries to act like a creep and fails. In the second half he becomes a creep and is awesome. But the star of this film is Mariko Tsutsui as the wife. Her face is hard-coded for WTF sadness. She does the Japanese thing of remaining calm in the face of super-WTF-ness, wonderfully. There are several big moments, impact moments, in the film where if I were her my head would have exploded. I had no idea how she would react. She's fantastic. The opposite of acting. She looks like she's processing the information given to her for the first time--not like she's acting the part of processing information. Bravo! When you see what happens to the kid it's funny, sad, super weird and then some. It remains understated which doubles the funny, sad, super weird and then some of it.
I have no idea what the ending says. It felt abstract and lame but didn't spoil things for me. I highly recommend the film to those who aren't bothered by bad eating-acting, or may not notice bad indie cliché scenes, and to those who are forgiving of bad script writing and acting during a film's setup phase.