[Will eventually add some things now that I've read the Vertical translation, but the following still covers most of what I'd say.]
Ririko is a Japanese supermodel, a beauty by virtue of reconstructive surgery, dieting, drugs, eating disorders, enormous amounts of pressure from herself and others, and experimental and dangerous medical regimens. She's had so much surgery her body's begun to break down -- and her mind is going with it, not helped by the amount of alcohol and illegal drugs she's taken, or by the self-destructive power plays of sex, as much an escape as any drug and far less pleasurable.
This is nightmarish, powerful, and obscene, and what's most horrifying is that the conspiracy/thriller/vaguely sfnal elements seem hardly an exaggeration from the real details of modeling. Ririko is a glorious monster, violent in excess, hating the world she's stuck in and herself for staying there, but convinced nothing else is worthwhile; and no one around her sees any options either. Even the few people who at first seem to offer kindness or escape end up being in the pay of Ririko's manager or the cosmetics industry or else they, too, are unable to see outside the culture of beauty: Ririko's assistant loses all conscience to her love/lust for Ririko, her passive masochistic desire to be subject to beauty; Ririko makes contact with her idolizing younger sister and in a sincere gesture of affection gives her money to diet and get cosmetic eye surgery.
A cop investigating deaths related to the clinic which does Ririko's work offers an "external" eye, but I am deeply skeptical of his masculine resistance to beauty; I don't think Okazaki problematizes him quite enough. Her world of beauty is a world of women mostly, women who are monstrous to other women, women who become monsters themselves.