The chime comes from the onboard announcement system on Japan's Shinkansen high-speed trains, where a short two-note signal alerts passengers that information is about to follow. Travellers began recording and sharing it because it instantly evokes the experience of riding a bullet train, from the quiet carriage to the station platform. As Japan travel videos, train-spotting clips and anime-adjacent edits spread online, the sound became a shorthand for departure, arrival and Japanese rail culture, and creators still use it to set a scene without needing any dialogue.