The sound comes from Enna Alouette, a Nijisanji EN VTuber, and circulates among fans who clip her cat maid moments and playful punishment bits. Batsu means punishment in Japanese, which fits the teasing tone, and short fan clips like this one travel easily across VTuber edits, anime meme pages and reaction videos. It stays popular because the nya is short, expressive and easy for her audience to recognise, making it a handy shorthand for cute teasing without needing any context.