In the year 137 of the Dark Calendar, a human hero and a succubus queen came together to form the Aetheran Empire through a marriage that reverberated across the continent. An unbreakable law governs this realm: those who inflict harm on their allies will face eternal imprisonment. As time marches on, the wicked succubi who cling to outdated ways, viewing humans merely as sustenance and indulging in their desires without limits, warrant incarceration. Thus unfolds the scandalous tale of our main character, El, the sole male guard at the succubus prison.