Banmei Takahashi - Doa AKA Door (1988)

A young housewife is not having a good day. Her husband is never home, the rent is late, her kid has caught the flu, and now – someone’s at her door. It’s a salesman, trying to pawn off some stupid thing or other. There’s no time to deal with it. Just tell him to go to hell, to peddle his goods someplace else. And then, when he doesn’t listen, she slams the door in his face. Or more accurately, on his hand. And this guy is pissed. The psycho salesman decides to teach her a lesson. He starts making phone threats. Soon the sick bastard has mustered enough guts to break into her apartment. He savagely torments mommy and child until the woman finally turns the tables… -Thomas Weisser, “Japanese Cinema: Essential Handbook”