Growing up in the US, you may think you should apply for Japanese colleges as a “Ryugakusei” (international student). However, you may not be regarded as an international applicant if you have a Japanese passport based on your family registry (Koseki) in Japan.
Instead, you need to go through an application process for Japanese students who attend overseas educational institutions. Students can choose to apply as (1) Kikoku-sei for (in most cases) April enrollment to pursue Japanese-based programs or as (2) students who want to pursue English-based programs that generally start in the fall.
When choosing an English-based program to apply to, you should pay attention to whether it is open to everyone, including Japanese citizens, regardless of where they attended high school. Rikkyo University’s PEACE program is one such institution that does not accept applications from students with Japanese passports.
Please keep in mind that colleges may change the citizenship requirement. When in doubt, contact the school’s admission office.