In a world where a gate leading to another world has appeared on earth, Aoi is an office worker working as an entry control bureau employee. One day, while dealing with ordinary people who have mistakenly entered another world, she meets Airhart, a prince of the demon tribe who has come from another world. For some reason, Aoi fell in love with him and decided to be his caretaker during his stay on earth. Aoi dreams of an ordinary marriage with modest happiness.