The first thing to remember about World War Two in East Asia was the prolonged conflict between Japan and China which had its direct roots in the Meiji Restoration of Japan. The two main periods of conflict were the First and Second Sino-Japanese Wars (1894-5 and 1937-45 respectively) and were essentially attempts to establish a Japanese empire in East Asia (if you are interested in the intellectual thought behind this I would really recommend reading some of Fukuzawa Yukichi's writings as they are fascinating). Japan was already at war with its primary enemy prior to 1939 and it is through this lens that we should really address the period.

Politically, the topic of war is volatile - Shinzo Abe changes his stance on the topic of war guilt to suit the national mood. Nationalism is at a current high with the diplomatic crisis of the Senkaku Islands regularly acting as a rallying cry for nationalists on both sides.