You are not Japanese but living in Japan for several years? Or you have just come to Japan?
Probably it is better to think about your resident status, because it shows what income is taxable and nontaxable. Some cases your foreign source income can be taxable in Japan.
Here is a brief explanation.
Under Japanese tax law, 'Resident' means a person who has a residence in Japan for one year or more. And Japanese residents are taxed on their worldwide income.
You came to Japan 2 or 3 years ago? You may be a 'Non-permanent resident'. Non-permanent resident means a person who does not have Japanese nationality and has had a residence in Japan for an aggregate period of five years or less within the last ten years. Non-permanent residents are taxed on Japan source income and foreign source income (only the amount remitted to Japan). It is important that you know how long you have been continuously living in Japan.
You are not categorized as Residents (not expected to live in Japan for one year or more, etc..), then you are Non-residents. Non-residents are only taxed on Japan source income.