Consider this panel:

![Transcription: 主役【しゅやく】はやっぱり　　　魔女【まじょ】のベフォーナよね　　　ビ　　　シッ　　　(from Aria Navigation 47)][1]

  [1]: https://i.sstatic.net/bbqaL.jpg

What do ビ and シッ represent? I'm conjecturing ビ is the mimesis for the raised finger, and シッ is the mimesis for the scarf as she turns around.