Given the title and the running time, I wasn't expecting much. Cheap J-horror starring an idol group, right? (I was correct about the idol group, incidentally. The girls in this zombie-besieged school are played by the members of Niji no Conquistador, a idol group themed around illustrating, cosplay and voice acting.)
Ultimately, though, I was surprised. It turns out to be good. I like the film's last act.
Don't expect too much, mind you. Cheap J-horror? Yes. Slightly goofy zombies? Absolutely. The zombie attack at the 13 minute mark or so is silly and unconvincing. In a proper zombie film, that hooting comedy character would have been bitten a hundred times while they're wrestling on the ground. The scene where Asami orders one schoolgirl to shoot another in the head also doesn't make sense if you look back on it later in the film, although one might hypothesise that she was testing her and had taken out the bullets.
If you're happy to watch a film like that, though, it works.
There's a school in the middle of nowhere, populated by seven students and a handful of teachers and staff. Zombies roam outside the gates. (The film calls them Gimps and they pack an electric charge that can make their eyes glow blue.) The teachers give lessons about zombies and on no other subjects, on which one or two of the girls will comment. The school's headmaster is a bit odd and intense, while another of the teachers is played by the great Asami Sugiura. (I love Asami. She always gives 110% to everything, although her films tend to be gross, trash and/or porn. Here she's in combat gear, talking like a thug and toting a ridiculously big gun. This works well and most actresses would have looked a bit silly trying to create the physical threat she manages here.)
I like the details. The girls eat jellied slime and are delighted if they have the good luck to find a caterpillar in it. You can use a zombie's severed but living head as an electricity generator. The shared dream about a child and its mother is sinister. Most of the film is doing a rather-too-good impression of bog-standard zombie nonsense, but it gets more interesting when the girls start investigating their own school and making questionable choices. They find the school library, for instance... and don't recognise it. They'd never been allowed in there.
The ending and its amusingly sadistic implications almost made me want to rewatch the whole thing. The film's probably not strong enough for that, but it has an interesting narrative and ideas to which you might not pay enough attention if you think it's just a cheap J-zombie flick. (Which, in fairness, it also is.) It also has 1980s Doctor Who incidental music and a cool theme song ("Undead Baby"), which I presume was sung by Niji no Conquistador. (Well, it's not literally and actually Doctor Who music. They haven't sampled a 1980s UK TV show... but that's what it reminded me of. I might even be able to nail it down further to the early 1980s. Their electronic keyboards feel more reminiscent of Saward-era music (Peter Howell, Paddy Kingsland, Malcolm Clarke, etc.) than of Cartmel-era, although my memory is probably exaggerating the difference between them.)
That was a pleasant surprise.