In the 21st century, humans and demons coexist, humans are humans by day and demons by night. However, the human-monster coexistence treaty signed 500 years ago between the human emperor and the monster emperor is about to expire. Millions of monsters from the monster tribe are ready to break through the constraints and take over the human world in one fell swoop. What I don't know is that there is a mysterious organization in the imperial capital that has received the news in advance and is ready to fight at any time.
Concept: Romantic fantasy