I don't think the Japs were ever keen to conquer the whole of China. Even if they were, the idea would have been quickly dispelled when they couldn't even capture a fraction of the heartland despite the heaviest casualties. They took that as an outrage and made sure the Chinese in other conquered territories paid the price by dying by the thousands in mass graves.
It is simply not in the Japanese psyche to give complete acknowledgement of their defeat in 1945, nor the atrocities committed in conquered lands. Up to day, no full recognition of the abuse of comfort women or the mass graves of Chinese lives. Also no sound no picture on the rape of Nanking, despite being well documented. Iris Chang after her tremendous work on the topic had a nervous breakdown and depression which led to her suicide.
To this day, also, the japs use the Yasukuni shrine to taunt China. Even as we speak, they are doing it:
http://www.chron.com/news/world/article/Japan-criticized-as-2-ministers-visit-war-shrine-5690296.php (article dated 15 Aug 2014)
A war which was started because of the Japanese ambition to secure raw materials and expand their industrial might became a bloody massacre and a carnage in which the worst atrocities were committed, and that haunted the older generation. Those who are still alive from that era are in state of cognitive dissonance about it.
