Mind-boggling title. Obviously it had to be watched, but to my surprise it's neither trashy nor trying to make you laugh.

It's about a gang of five malevolent schoolgirls. Sometimes they merely behave like repellent yobs that make you want to hit them, but usually they're worse. Their leader (Mizuki) shows the classic signs of being a nascent serial killer. I don't think she's actually murdered anyone, but the first thing she does in the first scene of the film is to throw a baby animal off somewhere really high, then not catch it. Their school has pet rabbits. Well, now it has fewer of them.

This makes her friends laugh. And that's in the first scene, mind you.

Meanwhile their teacher, Sawako-sensei, is four months pregnant. (Side-note: in Japan, women are pregnant for ten months rather than nine. I think they count it in four-week lunar months or something.) Anyway, Sawako's bump isn't big yet, but it's perceptible and the baby's starting to kick. Sawako is also a bit of a disciplinarian, not afraid to tear girls off a strip for talking in the library when the school's spineless idiot P.E. teacher hadn't wanted to do anything.

I repeat: this film is not silly camp. It's disturbing and nasty, then at the end shocking. Admittedly it's also kind of cheap-looking and I'm sure it's straight-to-video, but at no point does the movie cheat and start winking at you. The girls decide that their teacher having sex is disgusting, so they write "Let's Make the Teacher Have a Miscarriage Club" on the wall of their clubhouse and make a pledge among themselves with some rings they stole from a shop. (They don't even scrub off the writing afterwards, instead leaving it up there for anyone to see if they came in. I think that's arrogance, not stupidity. They don't think the rules of normal society apply to them.)

The film fails reverse-Bechdel, which is cool. No men talk to each other. There's almost no masculinity at all, in fact, bar two ineffectual teachers who get very little screen time. Almost everyone's female. We never even learn whether Sawako's married or not. Is she a single mother? Is she in touch with her baby's father? If so, what does he think? The answer to all these questions is "no idea". This is a good thing. It's just Sawako against the girls, with no scenes of trying to offload her problems on her husband. If nothing else, that would have diluted the intensity.

It also has a feminine ending rather than the formulaic masculine one I'd been expecting. I appreciated that too, especially since it had been so female-oriented from the beginning.

The film has characterisation. One of the girls shows signs of having a conscience, suggesting that she feels she's locked herself into this circle of friends and lacks either the strength or the courage to take on Mizuki. There's also a hysterically protective mother who's in denial of reality and lashes out at Sawako whenever she feels her darling's being threatened, for which the girls laugh at her.

The actors have very few screen credits, with Eisuke Naito having been brave enough not to cast lots of models and pop singers. The schoolgirls in particular will obviously never get anywhere in Japanese show business, because they're not pretty enough. Well, Mizuki might, perhaps. The performances are believable, though, with the teenagers being all too unpleasantly convincing in their roles. Even when they're being lumpish, it's the kind of lumpishness that comes across as an uncommunicative teenager rather than a bad actor. I thought they did their jobs.

It's not a gore film, although it does have an edge of exploitation cinema. It's grotty and faintly unpleasant to watch. It's not particularly impressive to look at, so if someone walks in while you're in the middle of it, they'll probably assume you're watching rubbish again. However it was rated as one of the ten best Japanese films of 2012 by Eigageijutsu, a Japanese film magazine. (Mind you, that said, Eigageijutsu likes obscure independent films, dislikes big studio productions and named four of Kinema Junpo's Top Ten films on its own Bottom Ten.) I've also seen it compared to Confessions, which made the shortlist for the 2010 Best Foreign Language Film Oscar. That's for subject matter rather than quality, of course, but this film's at least taking itself seriously enough that the comparison isn't immediately laughable.

Based loosely on a true story.