Burma: The Longest War
Very good account of the fighting in Burma by a British Japanese-speaker who was there as an intellegience officer.
Soldiers of the Sun: The Rise and Fall of the Japanese Imperial Army
Lots of pages but because the book spans quite a long period the WW2 part is not all that detailed. All in all, not that bad.
The Battle for Okinawa
Japanese account of the defence of Okinawa by an officer of the 32nd Army. Only just begun this book, but it looks promising.