I started writing chapter summaries and post them online just to make myself read it carefully. To write a summary I need to make sure I actually understand everything I read and not skip stuff when it gets difficult. As it turns out I understand this book just fine the first time through (well, with ample help from a kanji dictionary). To write the summaries I need to go back and reread each chapter all over again, and that makes reading it very slow and not much fun. I spend ages with this book, in other words, for little benefit.
And this book isn't really good enough to warrant all this effort. I mean, it's not nearly Dan Brown-level of bad (nobody has yet escaped from tall masochistic albino cultist hitmen by hiding in an Swiss bank's armored truck driven by the bank president1) but it's not exactly an immortal classic either. This is meant to be a quick, fun read on your daily commute. You're not supposed to reflect deeply on the characters or the story. When I have to go through each chapter twice to catch every last word and grammar point it turns from light entertainment into a tedious slog. Not fair to the book, and no fun for me.
So, from now I just read it through and enjoy the story for what it is. I'm piling up more Japanese-language books than I have time to read already, so I'll have no trouble finding something else once I'm done with this. Miyabe has a five-volume series on a copy-cat murder (模訪犯, Mohōhan) that Ritsuko is reading right now; that shouldn't take me more than, oh, three or four years to finish...
#1 Please - you write a serious, vaguely believable thriller, like John Grisham or Miyki Miyabe; or you do a lighthearted, over-the-top romp, like the Bond movies. You can't do over-the-top and serious at the same time. Doesn't work. I don't normally stop reading books partway through, but that armored-car scene is where I made a rare exception and gave up.