Blog
The Japanese have known for a long time that they are the easternmost country in East Asia, thus the rising sun touches their island first.

Then there's the sun goddess Amaterasu

(lit. "Shining Goddess") who sits as the queen of the Shinto pantheon. All the Emperors of Yamato are reckoned to be her descendants and thus the hereditary divinity of the Japanese Imperial house of Yamato.

In the 12th Century AD, we see the first official use of the moniker "日本" Nihon/Nippon (lit. "The Origin of the Sun") to refer to Japan, but only by the Japanese themselves. Koreans and Chinese would continue to refer to it by it diminutive name "倭国" Wakoku (lit. "Land of Midgets") till the modern era.

Only through the accomplishments of modern Japan did other East Asians finally relent to calling Japan by its own preferred name of "Nihon" in their respective readings of the two kanji.