One of the requirements that foreign nationals must meet before being allowed to naturalize as a Japanese citizen is that the foreign national have a very basic level of Japanese language ability. The way the foreign national can prove that he or she meets this requirement is by taking a simple Japanese language test as part of the naturalization process.
Permanent residency allows a foreign national to stay in Japan legally without having to worry about renewing a visa every year. In addition, becoming a permanent resident also lets the foreign national work in any field, not just the industry specified on his or her visa.
While most Japanese citizens acquire their citizenship at birth, Japan does not offer automatic citizenship to babies born within Japan. There are three ways a person may obtain Japanese citizenship by birth: 1) if the father or mother is a Japanese citizen at the time of birth; 2) if the father died before the child’s birth, but was a Japanese citizen; and 3) if the child is born in Japan and both of the parents are unknown or without nationality.