What is the capital of Japan?

The capital of Japan is Tokyo, which is a major economic and cultural center in the country and one of the most populous cities in the world. Established as the capital in 1869, Tokyo originally started as a small fishing village known as Edo. Its designation as the capital marked a shift in Japanese political power from Kyoto, which had been the imperial capital for centuries. Tokyo is not only the political heart of Japan, housing the Emperor's residence and government institutions, but it is also renowned for its vibrant mix of traditional and modern influences, featuring historic temples alongside towering skyscrapers.

In contrast, the other choices represent capitals of different countries: Beijing is the capital of China, Seoul is the capital of South Korea, and Bangkok is the capital of Thailand. Each of these cities has its distinct culture and significance but is not associated with Japan. Thus, the identification of Tokyo as the capital is both historically and contemporary accurate.