Obtaining Japanese citizenship

I was wondering how i can get Japanese citizenship when i am older, i am only a quarter Japanese though(mom is half japanese half korean) is it possible without marriage or naturalization?

You can only get Japanese citizenship by naturalization if you already don't have it by birth; marrying a Japanese citizen doesn't entitle you to citizenship.

Sorry to say, but the only way you can realistically get Japanese citizenship is to live in the country for at least 10-20 years and hope Immigration accepts your request for naturalization then.

unlike most developed countries Japan does not allow dual nationality/dual citizenship. This means you cannot keep your korean nationality or any other nationalities you have. Also in Japan there are huge problems because anti discrimination laws are not enforced, this is worth considering. The UN said this in 2010...
"Japan should adopt special legislation on the prevention and elimination of racial discrimination since the current general provisions included in the constitution and laws are not effective"
Jorge Bustamante, United Nations Special Rapporteur on the Human Rights of Migrants, March 2010