>>67913357That's KAF. She's the Suisei of non-Hololive singers. She performed at the Budokan (capacity 14000) over a year ago, which is one of Suisei's goals. I draw this comparison because it'd be like if Suisei just randomly appeared on stage in person out of nowhere.
KAF is part of Kamitsubaki Studio, and the venue where the webm took place seats over 13000 people. That is to say that the company is no stranger to huge, engaging VTuber performances, and their technology and production value is comparable (or greater) than Hololive's. It just sucks that a VTtuber of 5+ years, who has had the biggest virtual performances out of anybody, who belongs to a unit called "Virtual Witch Phenomenon", with a bunch of lore-related MVs, with the backing of the best virtual performance organizers in the industry, ends up singing in real person all of a sudden.