That's actually a tough question. I'm not reading any right now but there have been some books that have helped me along the way depending on what I was going through at the time. Read some Japanese history books and a number of Tokaido Road books including Lucia St. Clair, Kaempfer's Japan and Morton Olenik's Japan it's history and culture. Got a great perspective from those. Read most/all? Lowery's books but that was a while ago. 75 down blocks was good then I got into the "why" and read hidden karate which lead to Shotokan's secrets. Went through E.J. Harrison's Fighting Spirit book which led to Martial Musings.
I know you asked what are you reading now, but past books got me where I am now.
I loved Musashi, his life and writings and 100 years ago, NINJA by Erik van Lustbander. Unfortunately I haven't read many old Japanese books on martial arts.
How about a recommendation of say....2 books!