OP
There are basically 2 types of uni , public and private. Tokyo University (
Kyoto, Nagoya,
Hokkaido being other examples) is a public university. Keio, Waseda are examples of private.
Since you asked about Todai, I will focus on national universities which make up the bulk of public universities in Japan. National universities are similar to US state systems in quality. By that I mean the best ones are very good, and the "worst ones" are good.
Private unis can vary with the best (Keio) being very good and the worst being "not so good".
For national undergrad programs you need to take an entrance test (in Japanese )in general. BUT the government started an internationalization program called global 30.
http://www.mext.go.jp/component/a_m...icsFiles/afieldfile/2017/03/30/1383779_06.pdf
This includes both national and public unis (including both Todai and Ritsumeikan)
Start with this (above link) PDF to get an overview. Then if you Google -admissions global 30 Japan - That should bring up all the universities that are involved including their admissions requirements.
I do not know exactly what the requirements are, for undergraduate but your GPA is decent and your SAT is mediocre perhaps in the 60th percentile. These programs are offered in English.
Your biggest advantage is that you are a fee paying university student. If you can pay for school, your chances are much much better of getting in.
School fees for national University will be about $3000 admission fees/$5000 per year school fees-for a total of about $23,000 for an undergraduate degree plus living. Living cost varies greatly on how you want to live and where you want to live and can be as cheap as $700 and as high as $1400.
For public uni, there is a wider range of fees.
For this kind of basic information, you're better off searching yourself because Google can be your friend.
Once you done a search and if you have some questions about universities, I'm happy to help. But at the first stage, you should narrow it down to what you want to do-but don't give up on TODAI because they do have an English undergraduate program-I believe there in the sciences-as do many other good public universities. Google - Japanese universities and you can get more general info. The top public universities in Japan started with 9 imperial universities, now reduced the big 7. Google.
So good luck, but if you have a specific question please come back and ask-if you wanted to say something also please go back and tell us what happens.
Good luck