In pre-modern Japanese history, Tokugawa-shogun Era, 1601-1867 AD, the samurai-government closed the coutry to foreigners, national isolation. For more than 2 and a half centuries, the Japanese, those days, could live their lives, thinking only domestically, until Perry came to Uraga, a Japanese port, in 1853 AD.

Some readers may know Miyamoto Musashi, a famous samurai, who wrote "the book of five rings," 1584?-1645AD. The days of Musashi is former half of the 17th century.

200 years later, Japanese samurais, still, thought that it is fair to fight with samurai-swords, though it was the days that heavy machine guns were used in battle fields, in the Civil War in USA, in 1860's.

What I want to say is that this national isolationism in pre-modern Japan, is a lot related to tunnel-vision of a genral Japanese, today, since psychologically, many or most Japanese people close the door in mind to the outside world. I think,  one of typical examples is that generally, a Japanese is not so good at, or, is rather poor at English and other foreign languages. The people whose native language is Japanese are only 2% of the whole population on the plannet, Earth. If there are 100 people, only 2 persons speak and write Japanese for a native language. Such a situation shows as if the language, Japanese, is  a cipher or something. I think so.

This matter may be continued..., perhaps.