After each devil is born, the first thing he does is to give himself a name, and then the words will become material - a thing that records the devil's name. When people get these things and pronounce these words correctly and fluently, they can summon the devil.
The characteristics of each devil are in the name, either to achieve immortality or to achieve eternal wealth...
This is a story full of monsters and monsters. These mythical characters are around humans. They may pass by you or have friendship with you. Maybe the person sleeping with you is a goblin. Who knows?