Akuochi Hime to Yasashisugiru Maou-sama

A princess banished from her country ends up in the most peaceful place in the world: The Demon King's Castle"!
The Demon King is feared as "diabolical" and "ruthless". Humans are threatened daily by the Demon King. In this world where the human army and the Demon King's army are in constant conflict, the only hope for the human army is the existence of the "Holy Sword". However, the Holy Sword was sealed away and no one could get to it.
One day, Gemma Damascus, the princess of a country, easily pulls out the holy sword! Just when she thought she would be able to defeat the Demon King, the kingdom, a male-dominated society, refused to recognize the fact that a woman had pulled out the holy sword, and exiled Gemma from the country!
After wandering around for several days, Gemma becomes weak and her life is in danger, but an encounter saves her...a fantastic love story about an abandoned princess and a persecuted demon king's "revenge" in a different world!