Help! Copyright and NicoNicoDouga

[Silverbee]

https://www.nicovideo.jp/

This is a Japanese video hosting site, much like youtube. It seems similar enough and I thought it would handle the same when it came to copyright take down notices, but I was very wrong. I've tried multiple times to get my stolen youtube video taken down from that site but no matter what proof I send that I'm the owner of the video (the video has my name in it as the creator!), it doesn't work. After a few attempts, I managed to pry a decent answer from them:

We reviewed the additional information, but we cannot make a clear judgement on whether you have the rights to the content.

As such, we could not delete the video based on your request.

When we delete videos based on copyright violations,
we deal in accordance with the Japanese law,
the "Act on the Limitation of Liability for Damages of Specified Telecommunications Service Providers
and the Right to Demand Disclosure of Identification Information of the Senders"and the guidelines therein.

As such, in order to delete videos,
applicants need to provide information with
which we can make a clear judgement
as to whether a copyright violation has occurred.

However, as we are a service provider company,
we cannot give advisements, such as what kind of information is required
to make a clear judgment regarding copyright violations,
in the way a specialized agency would.

If you have questions about law content and interpretation,
or questions regarding the requirements to fulfill copyright violations
and the necessary materials to do so,
we kindly ask you to consult the advice of a legal office."

They won't tell me what I need to send to show that I'm the owner of the video. I sent them the original link, HQ screen shots of where my credits as the creator are, links to my site, and standard DMCA personal info.

I read through the definition of the "Act on the Limitation of Liability for Damages of Specified Telecommunications Service Providers
and the Right to Demand Disclosure of Identification Information of the Senders." I sent them whatever information that act asks for, but it didn't work. I combined both this and DMCA even, and it wasn't enough.

And again, the video's opening does credits me as the creator/owner. My name is in the video and that still isn't proof enough? I just can't get over that.

In the past, I had to take down the same video from other sites and DMCA has worked with no issues until now. I sent a DMCA notice the first time to NiconicoDouga as well. But after every rejection would send modified versions with more information/proof as possible, until I finally just asked what they wanted and got the above message.

Does anyone know the secret of dealing with NicoNicoDouga and the whole
"Act on the Limitation of Liability for Damages of Specified Telecommunications Service Providers
and the Right to Demand Disclosure of Identification Information of the Senders" thing?