"Makai" is a place where humans and monsters mingle. It is a world of survival of the fittest where humans and monsters fight each other. Luciola Lunatoria, a "hero", continues to defeat monsters, believing that peace lies beyond the battle. Until she meets Bilkis Draco, a merchant who buys up the goods of Makai. If you want something, you can win it through "business negotiations" rather than "force"! Even if the other party is a monster!! The story of inter-species trade begins!!