In the title role of Tatsushi Ohmori‘s “Mother,” Masami Nagasawa gives us one of the great screen monsters of recent memory.

Her Akiko Misumi is a Japanese “Mommy Dearest” — cruel, callous, self-absorbed, violent and still enough of a hot mess to appeal to any man who crosses her field of vision.

When we meet her she’s manic, grabbing her little boy for a day of playing hooky from primary school. When we last see her she’s dead-eyed and pitiless, her life of selfish narcissism and emotional brutality doesn’t phase her as she lacks a conscience.

A social worker (Kaho) is the epitome of Japanese good manners and understatement when she describes Akiko as “incapable.” We’ve seen what she did to her son, Suhei, played as a child by Sho Gunji and as an older teen by Daiken Okudaira.

“Mother” invites the viewer to play a grueling waiting game, its suspense stemming from the viewer’s growing desire to see the boy stand up to the woman who has made him cadge cash off relatives, steal, take beatings from abusive boyfriends and lie in blackmail schemes.

And even though Tatsushi (“Every Day a Good Day”) never heard the English expression “too much of a good thing” in drawing this story out over years with a running time north of two hours, his villainess rarely loses our interest or our eagerness to see her pay for her crimes.

“Mother” is a story of co-dependency and loyalty, of lives lived on the street and promise squandered because of an impulsive, martyred mother who A) has a gambling problem, B) ruthlessly uses men, including her little boy, and C) has the idea that her children are hers “to raise as I see fit” (in Japanese, with English subtitles).

Shuhei can never shake her, never defy her. Not after she ditches him at seven to run off with a new thug, Ryo (Sadao Abe), on a drinking/gambling binge. Not after she and Ryo use Shuhei to blackmail the hapless civil servant she talked into “watching” the boy while she left him for her latest misadventure.

Shuhei is who she sends to beg for money off her sister and parents. Shuhei, as a teen, is the one with a job she talks into getting advances from his boss.

We need only one scene to establish Akiko’s addiction. Her eyes glaze over when playing a pachinko (slot) machine. We never see her win, never see her pay a bill. It’s all-consuming, and the boy she brought into the world is just here to facilitate her habit.

There’s wailing and shouting in her encounters with her distraught and had-enough family. And there’s violence as Ryo enters and leaves their lives, slapping around Mother and the little boy who can’t protect her as he does.

It’s not giving anything away to say that a second child enters this world of flophouses and sleeping on the street, when they hit bottom. Akiko’s lack of self-control extends to all things, even the unfiltered insults she rains upon her boy when ordering him to skip school and babysit, or anything else she can command.

Through it all, Masami lets us see the instant calculating, the in-the-moment impulsiveness, with narrowing of the eyes when she sends the boy in search of the next need she orders him to fulfill.

Tatsushi’s storytelling is deliberate and slow, showing us the agonizing days an abandoned child spends eating uncooked noodles because Mother didn’t pay the gas bill, playing video games until the moment the power’s cut off, because guess what?

It gets to be too much after a while, and Tatsushi’s ending is drawn-out, downbeat and deliberately unsatisfying. But every Japanese filmmaker knows that not every monster movie ends up with Godzilla blown up and sinking into the sea.

MPA Rating: TV-14, violence, much of it against children

Cast: Masami Nagasawa, Sho Gunji, Daiken Okudaira, Sadao Abe, Halo Asada

Credits: Directed by Tatsushi Ohmori, script by Takehiko Minato and Tatsushi Ohmori. A Netflix release.

Running time: 2:06