In this world, humans and demons have been hostile for a long time, currently locked in a practical cold war. While humans view demons as enemies, demons don't really think much of humans. In fact, they wonder why humans are so angry all the time.

Humans imagine the Demon King's Castle to be a "terrifying stronghold of the Demon King's Army," but in reality, it is a very serious and professional organization. It consists of departments like General Affairs, Accounting, Hero Countermeasures, Monster Management, and Magical Research. It is a remarkably healthy workplace with paid leave, childcare leave, and overtime application systems. Alvan himself hates it when his subordinates overwork and strictly prohibits unreasonable overtime.

In this world, it is normal for both humans and demons to possess abilities, but Guest was bullied because no ability could be detected in them. They were eventually abandoned near the border, where the Demon King found them.