If I were to use a Japanese N64 game with my US N64 would it work?
Nope. N64 games are region-locked, even between Japan and the US. I'm pretty sure you can buy import carts, though - I remember a product called something like a "Game Passport".
Its just PAL and NTSC as far as I know.
But I a may be wrong.
NTSC = USA, Japan, Brazil (?)
PAL = Rest of the World such as England, Europe, Australia and those other places.
I got a game from England and it worked on my Australian N64 fine.
And yeah you can also get a region...thingy to play games from a different region, I have one to play my American Super Mario 64. I used to have more but my brother took them back.
the US N64 has tabs insie which prevent jap carts from being inserted.. open the machine and break the tabs then you're good to go..
it'll play jap games that way, but not euro