Japanese passport/citizenship issue

I'm sure someone has asked this question before, so I apologize for being redundant. I am a Japanese national who's in early-40's. I've been in the US since the age of 22. I am going to get my US citizenship interview in one week time. Assuming I pass the interview, and become US citizen then, then what will happen to my Green Card? I am assuming that the INS will take it away from me. I have a valid Japanese passport, but it will expire on my birthday next year, and at the time, if I decided to renew it, then what about my Green Card? Wouldn't Japanese embassy/consulate want to see that I am a Japanese national living in the US legally with valid Green Card?
If I don't get to renew my Japanese passport, it is really not a big problem for me, but I'd like to know if there's any Japanese person here in the US who became the US citizen and still could somehow renew his/her Japanese passport without the Green Card. Please help!

I would advise you to search this site and see the other threads on this issue, because there are a few offering an array of opinions and suggestions, one of which is to renew in Japan if possible. I wonder, though, if the Japanese consulate is legally entitled to ask you for your green card. erhaps itwouldbeadvisable to seek a legal opinion.

Or you can just renew it now, there's nothing that says you can't renew it early.

Thanks for your suggestions! :)) I did do some search on this site, but I didn't find any that dealt with a situation similar to mine. :((

Here, all I really want to know is:
1. Is it possible to renew my Japanese passport without Green Card after I become a naturalized US citizen. At the time of renewal, I will not have the Green Card to prove my legal residency as a Japanese in the US.
2. Is it possible to renew my Japanese passport in Japan without jumin-hyo(residency registration) under above mentioned circumstances? Since I do not live in Japan, my name is not on my family's jumin-hyo.

As I stated in my original question, if I can't renew it after I become the US citizen, it really is not a big deal, however, I would like to get the clear answer to both questions from a Japanese person in the USA who became the US citizen, so at least she or he would know about what to do with the Japanese passport. My citizenship interview is only a few days away, and I just want to put my mind at ease! :)) Thanks!