"Butter-Fly" was performed as the ending theme song to the 1999 film Digimon Adventure and later became the opening theme song to the television series of the same name.[1] It was the first time Wada had sang a rock song, as he originally performed "Butter-Fly" as a ballad.[2] Originally released on April 23, 1999,[1] the single was re-released on August 1, 2004 with new CD artwork to commemorate Digimon Adventure's 5th anniversary.[3][4] The success of the song gave Wada the title "Immortal Butterfly Anime Song Singer."[5]