How long have you studied Japanese? You will have it really difficult if your Japanese aren’t at least good enough for long conversation. Colleges aren’t as nice as high schools
There is a program called Global 30 in Japan developed to attract international students to universities all over Japan. In fact, you can’t qualify for it if you are Japanese. It looks like if a decent undergrad option. If you are a US citizen, you are better off doing medical training in the US. Japanese trained doctors spend a lot less time in school, and you might not qualify as a doctor to practice if you try to return to the states to live and work.