Well, there's a title to turn your hair white. The English-speaking world prefers to know it as Prison Girl. Can't think why.
I watched it because of Asami, who plays the title role. I'll watch pretty much anything with Asami in it, although as it happens this is one of her straight acting roles. She's not unhinged this time. She's playing a housewife who's in a sexless but otherwise reasonable marriage. They've been together for two years and they don't have any children yet, because Ayaka wants to return to work. They get on well. Her husband's nice and considerate. Their conversations at the breakfast table feel comfortable, although you might see a danger sign in the brief scene where Ayaka keeps silent about Kenji's table manners.
At the same time, though, Asami's also playing the heroine/victim in a "women in prison" exploitation film. That's where the title comes in. These can be slightly silly (e.g. the squeaky rubber sounds when a guard grabs Ayaka's boob), but they're also a torrent of filth, humiliation, nudity and abuse.
Housewife-Ayaka keeps having dreams about being Prisoner-Ayaka. She's been having them since she's in junior high school (yikes), although she tells her psychiatrist that they weren't this extreme before.
This is a pink film, obviously. It stars porn actresses and it's filthy as hell. However a Japanese pink film can be pretty much anything its director wants it to be and this one's from Naoyuki Tomomatsu (Eat the Schoolgirl, Stacy, Vampire Girl vs. Frankenstein Girl and many more). It's actually quite a good, difficult film with loud symbolism and a serious tone. Asami's very good. It's surprisingly odd for an Asami fan to see her in a normal, domestic character like Housewife-Ayaka, but she does very well and turns the film into a surreal hour-long character study. Housewife-Ayaka grounds the other Ayakas and makes them stronger by contrast. Obviously she's sexually frustrated, but you don't know where this is going or how she really feels about her husband and her marriage.
There's lots of metaphorical blood. There's a decision at the halfway point that made me cringe because there's no way in the world that that will turn out well. There are extreme developments as you lose track of what's real and what's a dream.
Did I enjoy this film? Nope. Would I recommend it? Nope. It's not a particularly comfortable watch, but not in the way you'd expect from its title. The "women in prison" content is all just a dream, so you're not particularly bothered by that. It's not a Female Prisoner Scorpion film or anything. You're watching a surprisingly gentle, domestic study of a marriage between two people who in most respects get on well. It's almost dull. However you'll know in the pit of your stomach that the film's building towards other things.