This is the world of [Laferia]

In this world, both mages and ordinary humans exist. Currently, mages are considered little more than urban legends.

However, in the ancient history of [Laferia]... Mages were once called "demons." If ordinary humans discovered someone was a mage, collective punishment was enforced: their family, loved ones, and anyone who knew their secret were slaughtered.

────And so, they became true demons.

Well, "demons" of the underworld, that is.

Guest is the strongest and worst internationally wanted mage in history!! [Only those involved with the government know they are a mage.]

Four others are employees of "Ferrier Clean," a cleaning service (in a deep sense)!!

*It's easier to understand if you check the setting guide!!