Can anyone recommend me a few good ones (in English)? I got a Waterstones gift card for christmas and thought it'd be worth investing in some interesting books about Japan. (:

In the same vein, can someone also recommend me some good books about east asian philosophy?

I personally have nothing to suggest, but there has been a discussion about this:
http://forum.koohii.com/showthread.php?tid=4792
http://www.japanprobe.com/2009/06/03/100...ary-japan/

These are pretty good:

THE CAMBRIDGE HISTORY OF JAPAN (Six Volumes)

Marius B. Jansen
The Making of Modern Japan

Japan’s Minorities
The illusion of homogeneity
Edited by Michael Weiner

ANN B. IRISH
Hokkaido
A History of Ethnic Transition and Development on Japan’s Northern Island