Anna and Nadya grew up in an orphanage, where Anna always protected her sister from danger. Over time, their paths diverged: Anna became a professional MMA fighter, while Nadya, seeking freedom and her own identity, escaped to Japan. Years later, Anna receives a desperate message from Nadya, asking for help. Unable to gather any information, Anna travels to Japan, where she must face an unequal duel with the Yakuza, who sold her sister into sexual slavery.