Shirakami Fubuki is one of Hololive's founding VTubers, a white-haired fox girl known for her gentle voice and playful personality. The word "nani" is a staple of Japanese speech, equivalent to asking "what" when something confuses you, and anime fans hear it constantly in subtitled shows. Short voice lines like this one get clipped from livestreams and spread across soundboards and meme edits, where they work as quick reaction sounds. It stays popular because the confused tone is universally relatable and instantly recognisable to VTuber fans.