Do I have to have a VISA in the country I am traveling to??

I am going from New York, USA - Beijing, China (for just 16 hours) - and then on to Tokyo, Japan

I am also doing the same thing, but reversed for my travel back.

I see it says you need a entry permit for the country you are traveling to, but we don't need entry permits for Japan. Can you clarify if I just show my tickets and passport?