The Hino RK is a rear-engine bus chassis built by Japanese manufacturer Hino Motors and widely operated by bus companies across Indonesia and Southeast Asia. Enthusiast communities, often called bus mania groups, film, spot and share clips of specific chassis and engine sounds online. Short recordings linked to the RK spread through those videos and edits before being cut down for soundboards. The double version remains popular because fans can identify the model from sound alone, turning a brief mechanical burst into an in-joke and recognition cue.