How can I study in Japan?

I actually need help on a few things, it's not as simple as my thread topic.

I'm a dual citizen of both Japan and the U.S. I grew up in the U.S. and have limited proficiency with Japanese (language). I'm thinking about going to school in Japan, it seems like a pretty exciting opportunity, but in order to make an informed decision, I need help from somebody, preferably not named ''Google'' (I haven't been able to glean a solid answer.)

As a Japanese citizen who has never really lived in Japan for an extended amount of time (past what is allowed for a temporary visa) my questions boil down to these:

1. Will I need a student visa, or can I apply for residency in Japan, with my grandparents? Could I just move in with them and renounce my U.S. citizenship?

2. Am I potentially elligible for government financial aid to attend school? I hear that they make international students provide proof that they are totally financially secure before ever granting a student visa, and if becoming a full-blown citizen/resident will give me a leg up on foreign students, then so much the better.

3. If I don't need a student visa, does that mean I can work while I'm in school?

4. What about student loans? I know they generally don't approve foreigners, but I could potentially on-paper be 100% Japanese citizen & resident.

5. Is there anything else I need to know that I haven't thought of yet?

This sounds like a silly request, but I'd like to know that my answers aren't comnig frmo just anybody, so if you don't mind, if you have an answer, please post along with it your credentials and occupation, or mention if you have experience dealing with a similar matter.
Thanks in advance.

If you are a Japanese national, then you don't have to worry about student visa or whatsoever at all. (Whether you want to renounce your US citizenship would depend on what you want to do/where you want to live later in your life, and also your age. The Japanese government does not permit dual citizenship beyond a certain age, but they don't have to see your US passport, right?)

I would be more concerned about the Japanese language proficiency - you need to be at JLPT level 1 or 2 to be admitted to a Japanese university/college, as all lectures would be in the local language. You would probably need to attend a Japanese language school first before you enrol in a university. Of course you could go for universities like ICU or International dept. of Sophia University (sorry I forgot the official name) where courses are (at least some of them) are in English, and there is Temple University in Japan (that's an American university), but that would not really help if your intention is to stay in Japan long term.