Are you From another Country? No Disrespect meant at all, but... If you are,

I wouldn't expect you to Understand our Constitution, or the Value we place upon our Liberties...

I wouldn't expect you to Understand Freedom or Liberty, when it is something that you yourself have never been allowed to have or experience...

Why didn't the Japanese invade the US mainland during WW2?

The Second Amendment... That's why.

Admiral Isoroku Yamamoto - “You cannot invade the mainland United States. There would be a rifle behind each blade of grass.”

And let's get something Straight...

The Second Amendment does not say "The Right of the Militia to keep and bear Arms shall not be Infringed"

Instead, it Acknowledges the necessity of the Militia, and Guarantees that:

"The Right of the People to keep and bear Arms, Shall not be infringed."