Onegai Muscle is the opening theme of the 2019 anime How Heavy Are the Dumbbells You Lift, a comedy following high-school students who join a gym and learn about training. The song's catchy, high-tempo style made it a natural fit for short-form video, where it spread through workout edits, gym memes and anime fan clips. Because the chorus is instantly recognisable and tied to exercise, creators still reuse it to signal effort, motivation or a comedic training montage, long after the series first aired.