Another underrated book you should read is Night Train by Judith Clarke
I seemed to have seen this book before because it looked vaguely familiar (or there's a book with similar cover to it that I've read), but anyway I'm quite intrigued what this book is all about—I mean you seemed too attached to it so I guess it's has a profound message that left a mark on you. I'll try to look for a copy of it...and I'll see if it'll also leave a mark on me.
Thanks for the recommendation...I don't know if this is underrated, but there's a certain novel that came to my mind while reading this one, and it's Memoirs of A Geisha by Arthur Golden. I read it way back, my first year in junior high, and up until now, I still can remember it. So I guess it's worth sharing :)