Listen to Main Theme (from "Grave of the Fireflies") (Piano and Rain Version) online. Main Theme (from "Grave of the Fireflies") (Piano and Rain Version) is an Unknown language song and is sung by Quiet Gaze. Main Theme (from "Grave of the Fireflies") (Piano and Rain Version), from the album Peaceful Anime (Piano and Rain Version), was released in the year 2022. The duration of the song is 2:00. Download Unknown songs online from JioSaavn.