1. You can probably take the required courses through OPEN UNIVERSITY the semester before you hope to get it. https://www.calstate.edu/attend/professional-and-continuing-education/Pages/open-university.aspx 2. You should consult with your Japanese university academic advisor (who can contact the CSU campus you want to enter) to see if any of the courses you already took can be applied to one of the Golden Four courses. 3. You could take these courses at a community college (best way IMO).
I am American and have been teaching ESL in groups as well as helping friends learn and practice English. The Japanese language and culture are an interest of mine, so cultural exchange and friendship is compensation enough for the help I provide. If you're interested in light conversation to practice your English or want guidance on methods of study, please reply or email me. I'm happy to help.
ご存じの方はご連絡いただけると幸いです。