>>59908096There doesn't seem to be a definite official term, I looked for all three on Japanese Twitter and there are a lot of results for both フブニウム and フブキニウム, but フブキニウム seems to be the more common one. There are some hits for 白上ニウム but they are very rare, so I guess that one isn't used much at all. I'm not sure if she has ever said herself, but I have vague memories of her mentioned it once after her unannounced disappearance a few months ago. I went looking for it, but I couldn't find anything on twitter or her first stream after she returned where she briefly talked about her disappearance, so I guess my memory was wrong or it was on another stream after all. I saw a bunch of people say フブキニウム in the chat during that stream, too, so I guess that one is the clear winner. That image is from a random Twitter post I found while searching, as well.