Nyanpasu comes from the anime Non Non Biyori, where the character Renge Miyauchi uses it as a distinctive greeting. The series began in 2013, and the line quickly became a recognizable anime catchphrase in clips, compilations, and fan edits. Its popularity comes from how unusual and instantly cute the delivery sounds, making it easy to reuse as a greeting, reaction, or comedic cutaway. In anime meme circles, it often appears alongside other short character catchphrases like Tuturu.