There was once a girl known as the "Night Princess of the Darkness." Having commanded the demons of the imperial capital, she was defeated by a young man in a white military uniform. Hinako, who returned to the past from the end of her life, lived hiding her supernatural powers in order to avoid a gruesome future. However, one day, Ryuga, the captain of the "Underworld Central Affairs" who killed her in her previous life, appears. Hinako refuses to cooperate with him, who seems to have been ordered to investigate her background, but he reappears with a letter of engagement to Hinako...