Renika-hime to Seiyoku no Akuma / Princess Renika and the Demon of Lust

The Kingdom of Parthia is the largest and most populous empire on the planet Serif. It occupies four of the five continents. The empire is ruled by Princess Renika von Saxony on behalf of her mother, the Great Queen, who recently fell seriously ill. Against the backdrop of weak control of power by the princess, a numerous opposition with its own foundations and ideals is growing within the empire. The political immortality of the royal family was shaken by the fleeting illness of the queen. 

"This empire must be divided into small states!" - cries of dissent kept reaching Princess Renika, but she never liked politics, so she paid no attention.

However, everything was decided in one night. Thousands of rebels captured the castle. The princess and the sick queen were taken prisoner, and a usurper ascended the throne...