General Toshio Tamogami's essay, posted on the website of a Japanese hotel and apartment developer, was expected to spark anger in China and South Korea, where memories of Japan's wartime acts and colonisation run deep.
Beijing and Seoul say Tokyo has failed to properly atone for its invasion of the Korean peninsula, Taiwan and parts of China.
"His views are different from the government's. It is not desirable for him to stay in the job," Defence Minister Yasukazu Hamada told reporters soon after the essay was made public.
In the essay, titled "Was Japan an Aggressor Nation?" Tamogami said it was "certainly a false accusation" to say Japan was "an aggressor nation" during the Second World War.
"The current Chinese government obstinately insists that there was a 'Japanese invasion,' but Japan obtained its interests in the Chinese mainland legally under international law through the Sino-Japanese War, the Russo-Japanese War, and so on, and it placed its troops there based on treaties in order to protect those interests," he wrote.
He also claimed life under Japanese occupation was "very moderate" and cited a rise in the population on the Korean peninsula during Japan's 1910-1945 occupation as "proof that Korea under Japanese rule was also prosperous and safe."
Gen Tamogami also claimed that Japan was tricked into attacking Pearl Harbor on Dec 7, 1941, by US President Franklin D Roosevelt.
Japan was "snared in a trap that was very carefully laid by the United States in order to draw Japan into a war," he wrote.
"Roosevelt had become president on his public pledge not to go to war, so in order to start a war between the United States and Japan, it had to appear that Japan took the first shot. Japan was caught in Roosevelt's trap and carried out the attack on Pearl Harbor," he wrote.
Gen Tamogami ended his essay by saying Japan should reclaim its glorious history and warning that a country that denies its own history is destined to fall.
Japan renounced its right to wage war in its 1947 US-drafted constitution, and Tokyo has repeatedly expressed remorse to its neighbours for its colonial rule and wartime aggression, including in a 1995 statement by then-Prime Minister Tomiichi Murayama to mark the 50th anniversary of the end of the war.
But Japan has struggled to convince Asian critics - and victims - of its contrition because of a strong nationalist presence in the Japanese government. Last year, a group of nationalist lawmakers from the ruling Liberal Democratic Party angered China by saying the generally accepted death toll in the "Rape of Nanking" massacre was grossly inflated.
Gen Tamogami's essay won a writing competition organized by a hotel and condominium developer, Apa Group, which published the prize-winning article on Friday.
http://www.telegraph.co.uk/news/worldnews/asia/japan/3331691/Japanese-general-claims-Japan-was-not-an-aggressor-in-Second-World-War.html