The sound comes from Project Sekai Colorful Stage feat. Hatsune Miku, the mobile rhythm game developed by Colorful Palette and published by Sega. It was released in Japan in 2020 and worldwide in 2021, building a large fanbase around its Vocaloid cast and touch-based charts. Long hold notes are a core mechanic, so players hear this chime constantly during play. Clipped and shared by fans, it became a handy shorthand online for focus, patience and barely holding on.