Butter-Fly was first released in 1999 as the opening theme for Digimon Adventure, sung by Koji Wada and composed by Hidenori Chiwata. The song became closely tied to the series and returned in a new arrangement for Digimon Adventure tri in 2015. This off vocal version removes the singing, leaving the familiar instrumental melody that fans recognise immediately. Online, that short hook has been reused as ringtones, message tones and alert sounds, helped by nostalgia for the original anime and the tune's bright, memorable opening notes.