Isolated language are very few such as Basque used in Spanish-French border, Korean language and Ainu language. There have been many theories in origin of Japanese language. Some linguists say it is related to Tamil language spoken in India and others say it is related to Polynesian languages. The similarities between Japanese and Korean have been argued for many years but nobody can prove they are cognates. The Japanese language is spoken in many other countries besides Japan, especially in North and South America.
Brazil has the largest Japanese speaking population in the Americas.
Well, I hope by now you don't feel intimidated about your struggle with Japanese language but rather you should be proud of yourself that you are studying one of the most unique languages in the world.