Japan is known as a highly ethnically homogeneous country. About 98% of the population is Japanese. The language which is spoken in Japan is mainly Japanese.
However, the situation has been changing these days.
First of all, more and more Japanese people are interested in foreign cultures and languages. Even though Japanese is our native language, the number of people who speak English as the second language is increasing.Some Japanese study a foreign language other than English.Similarly,as for culture, Japan has been adopting various foreign cultures.
In addition, I think the percentage of foreigners in Japan will increase in the future.As the aging population is becoming a problem in Japan, I think there will be a shortage of workers in some industries.As a result , Japan might accept more immigrants in the future.