The Imperial Navy was led by men who in hindsight we can see lacked strategic vision. The Japanese armed forces committed some strategic blunders. Firstly they could not for whatever reason annihilate the US aircraft carriers at Pearl Harbor. They also had no plan for a landing on the east coast of the USA. Secondly they started an Indian Ocean domination exercise in March 1942, but had no plans to invade India from Ceylon after they had achieved complete superiority in the Indian Ocean and Bay of Bengal.
The Japanese task force led by Admiral Naguma established a stranglehold
In case the Japanese General staff had widened their strategic vision and after having achieved complete domination of the Indian Ocean, it was an easy matter to Invade India. The British at that time had hardly any troops in South India and what ever force available was placed on
In addition Gandhi had launched ‘Quit India’ movement in 1942 and the entire country was in ferment. This was a ripe moment for the Japanese to strike. The fact is that this option of an invasion of Ceylon was never discussed and a golden opportunity was allowed to lapse.
Perhaps one factor was the US fleet which the Japanese were intent on annihilating to dominate the pacific. But the fact remains that the Japanese in 1943 did advance into Burma and from there they had plans to proceed to Delhi with the Indian national army fighting on their side.
This is one of the if’s of history. What if in 1942 the Japanese had mounted an invasion of South India.? There is ever chance hat the war would have taken a different course and maybe India would have been rid of the British earlier. Though whether the japs would have been enlightened conquerors is another matter.