Lost Child, Lost-and-Found Police Station

In 19XX, Royal Air Force pilot Chihaya Aine, after experiencing the cruelty of war, fled to Edenia (USA) across the ocean, living a aimless life until one day, she met a detective named Takamatsu Akari. By chance (through the power of a succubus), she decided to follow the detective to Golden State (Los Angeles) to find out what was going on and save the precarious peace and order of Golden State (Los Angeles).