Where on the earth is Japan located?

If you are in Europe, Japan is in the Far East, and you would get there by heading east starting from the southern tip of the Italian Peninsula.
You would go through Athens, continue to make your way east along the 36 degree north latitude to Iran, and then after traversing the Asian Continent across China and crossing the Sea of Japan, you will reach the center of the Japanese islands.

If you are in America, go due west from San Francisco and you will eventually reach Tokyo.
New York is on the same latitude as Aomori Prefecture, the northern part of Honshu (the main island) of Japan.
Paris is on the same latitude as the northern part of Hokkaido and London is located north of the northernmost tip of Japan.