/vt/ - Virtual Youtubers

Suspects:
>Yozora Mel
Rrat-tier because this was announced before Mel termination, unless she knew it'd come to that and Aogiri somehow had a model and promotion materials all available without a talent in mind.

>a previous talent from ZERO Project

This is the most likely theory currently, look at picrel. That is the graduated Tsumugine Rei from ZERO Project (aka current ChumuNote) account retweeting the Aogiri announcement of the new girl, and she also retweeted the self-introduction tweet from Popura.
But it can't be Rei herself, because she's already ChumuNote, which suggests this might be one of her previous peers.

What was ZERO?
Just another disbanded group. You might know Pururu and Sorahoshi Paru (and ChumuNote) who went indie and found success after this group disbanded.