Double Dragon II: The Revenge[a] is a side-scrolling beat 'em up produced by Technōs Japan originally released as a coin-operated arcade game in 1988. It is the first sequel to Double Dragon, released during the previous year. The sequel involves Billy and Jimmy Lee in a mission to avenge Billy's girlfriend Marian after she is shot to death by the Black Warriors leader Willy, who is retaliating against the Lee brothers after his defeat at the end of the previous game. Double Dragon II was initially developed as an upgrade kit for the original Double Dragon, but evolved into a stand-alone game due to an increase in memory size, resulting in the developers reusing assets for both games.[5]