That's not Natsuki_(Blue Archive), but rather a new mob that was introduced in the latest story chapter.

I had seen a screenshot that had her name as something like "Gymnastics Club Member" (I was completely off lmao) but I can't find it again to confirm it so that I can create a tag for her. If anyone can find a screenshot with her ""name"" that would be every appreciated.

Found it, Track And Field Club Member (Blue Archive).