LT visa naturalized US with Koseki

I'm a Japanese born but naturalized US citizen, I haven't done denaturalization documentation to the Japan Embassy but I had been thinking about obtaining my koseki (I am listed and parents are Japanese) for a long term visa (child of Japanese) but I haven't done the denaturalization documentation that changes the koseki. Would that affect the long term visa application or would it be fine since I'm trying to get a visa instead of claiming I have dual citizenship?

Sorry, I am a bit confused. If I understand correctly, you were born a Japanese citizen and then later naturalized as US Citizen but did never report this new citizenship to any Japanese office.
Yes, you SHOULD have given up your Japanese citizenship when you became a US citizen, but my understanding is that the Japanese government isnft checking automatically. So if you hadnft given up your Japanese nationality, you are still Japanese. Your passport might be outdated, but that doesnft mean that you are no longer Japanese. So unless you want to be super correct or you are super clumsy (or you want to run for some political office in Japan) why not just get a new Japanese passport and just BE Japanese. The Japanese government is never going to be the wiser that you also have US nationality.

@LikeBike

Your understanding is incorrect. AK lost his Japanese citizenship automatically. It doesn't matter if he reported it or not.

They ask on the the passport application if he has another citizenship. So he has to lie about that. The Japanese embassy may also ask for proof of his visa status in the US, so he can get caught in the lie.

@AK
Why don't you just report your status to the embassy? If it's too much trouble, then just apply for the visa and see how it goes. I have known someone who actually is currently a Japanese citizenship but applied for a Child visa and received it. I don't know how that one got through but it did. That individual has been living in Japan for many years as a foreigner, so you never know.

report your lost of Japanese nationality to the city office. then, everything starts from that stage.