Otagei, also spelled wotagei, is a fan dance and cheering style that grew out of Japanese idol concerts, where supporters perform synchronized arm movements, spins and jumps while waving glow sticks in time with the music. Clips of these routines spread through concert footage and online video, turning the loud, coordinated crowd performance into a recognizable part of idol culture itself. The sound remains popular because it instantly evokes that communal concert energy, making it a handy shorthand for fandom, excitement and over-the-top support in dance videos and edits.