The game's story begins with Filena, a girl raised as a boy by her grandfather Zenna. Filena is raised as a boy because the Empire ruling the country forces girls into prostitution and turns boys into gladiators. After turning 16 Filena prepares to make her debut in the imperial coliseum, however before the battle she and her fellow gladiators are assigned concubines. Filena ignores her assigned bedmate, Lila, but Lila forces her way into Filena's room and learns the truth about her gender. Filena later fights through the gladiator ranks and discovers that their battles to the death are all scripted by behind-the-scenes writers. Filena then sets off with Lila on a quest to bring down an empire and reclaim her rightful place in a lost kingdom.
Eternal Filena follows the adventures of Filena, the only survivor of the royal family in the ocean kingdom of Filosena which is destroyed by the ruling empire. She is brought up as a boy slave and gladiator, and enters the gladiatorial games designed by the Empire to keep the masses happy. Young slave boys are trained as gladiators and girls are forced into prostitution. Filena befriends Lila, a slave assigned to be Filena's bed-mate before her first gladiatorial bout, and sets off on a journey with Lila to free her homeland from tyranny and discover her true past.
