Mary Tudor is imprisoned in a POW camp that the prisoners residing in it call “Helheim” within the Kalmar Empire. One day, while trying to protect her “big sister” Elizabeth, she is beaten by the prison guard until Elizabeth abides by the guard’s request and Mary falls unconscious. During her sleep she recalls memories of her past life as a male and thus is provided the knowledge to help strengthen herself to escape the prison camp. Join Mary as she uses exploits of the game system that the world she reincarnated in is based on.