Tokyo is the Capital of Japan.

东京是日本的首都。

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Kyoto used to be the capital of Japan.

京都曾是日本的首都。

《新英汉大辞典》

Do you know which city is the capital of Japan?

你知道哪个城市是日本的首都吗？

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As the cultural capital of Japan, traditional arts are actively cultivated in the city.

BBC: Kaiseki-ryori: Japanese haute cuisine

Japan is within range of these rockets and has been taking precautions, including setting up batteries of US-made Patriot anti-missile systems around the capital and sending two warships to the Sea of Japan, with orders to shoot down any missiles fired towards the Japanese islands.

BBC: Kerry urges North Korea to join regional dialogue

Again, I expect the flow of capital out of Japan to continue, and I remain very bullish about non-Japanese stocks.

FORBES: Put Some Money in Japan