The C word has now been said

Well, that and the fact that it would be really hard for them to move an army of men across the Pacific undetected.

Our govnmt. Isn't going to confiscate guns.

What stopped them invading Australia then? They bombed one city, but never set foot on our soil.

Japan attacked Pearl Harbour as retaliation for what they saw as an act of war - a US embargo on oil trade to them. Pearl Harbour was intended to cripple the Pacific fleet, not to enable an invasion of the US, but so that Japan could invade another place - the Dutch East Indies, rich in oil.

They didn't invade the US because it wasn't what they were intending to do. Nothing to do with guns possessed by home-owners.

Debate between the Army and Navy
Japan's success in the early months of the Pacific War led elements of the IJN to propose invading Australia. In December 1941 the Navy proposed including an invasion of Northern Australia as one of Japan's 'stage two' war objectives after South-East Asia was conquered. This proposal was most strongly pushed by Captain Sadatoshi Tomioka, the head of the Navy General Staff's Planning section, on the grounds that the United States was likely to use Australia as a base to launch a counter-offensive in the South-West Pacific. The Navy headquarters argued that this invasion could be carried out by a small landing force as this area of Australia was lightly defended and isolated from Australia's main population centres.[2] There was not universal support for this proposal within the Navy, however, and Isoroku Yamamoto, the commander of the Combined Fleet, consistently opposed it.[3]

After the Japanese decimated our fleet in Pearl Harbor Dec 7, 1941, they could have sent their troop ships and carriers directly to California to finish what they started. The prediction from our Chief of Staff was we would not be able to stop a massive invasion until they reached the Mississippi River. Remember, we had a 2 million man army and war ships... all fighting the Germans.
So, why did they not invade? After the war, the remaining Japanese generals and admirals were asked that question. Their answer... they knew that almost every home had guns and the Americans knew how to use them. The world's largest army.

...and most sane people in the rest of the world.

They could have, but as stated, they never intended to invade. The US mainland had nothing they wanted. By bombing Pearl Harbour, they disabled the Pacific for long enough to get what they needed. It wasn't a matter of finishing what they started - you just seem to think they wanted something different to what they were actually after.

You can say that armed civilians are the reason they didn't invade, but it's simply not true. It was simply not an objective, and offered no incentive to become one.

I do know that December 21, was the shortest day of the year
Here in the US and now the days will start getting longer.

What do you mean?

I really don't think gun controls have anything to do with invasion, you have a powerful army to defend yourself, something you didn't have the "right to bear arms" was implemented and therefore had a point. In the Uk it was law that each household had an archer, bow and arrows in medieval times as they might be needed to fight for the country...we have moved on from that ( but the law may well still exist for all I know).

And it was the longest day of the year in Australia, and the days start getting shorter from here. What does that have to do with the price of wool on a dry day in Donegal?

So if I understand what you are saying is , You do not think
The US Constitution's 2nd Admendment gives American Citizens
The right to buy a gun that is legal to sell in America to the ordinary
Citizen who fills out the proper paperwork and goes through the
FBI background checks.

Now I am not talking about a Class 3 dealer / buyer (mostly
Gun collecters) who can buy unaltered military weapons like
Assualt weapons. (weapons that are full auto or have a selecter
Switch that allows the shooter to choise single shot or multiple
Shots with each pull of the trigger). This class of dealer/buyer
Can also purchase/sell working military tanks etc.