Kaito pulled out a document. "The original treaty, signed seven hundred years ago, states that the Demon Lord's domain provides magical barrier maintenance that prevents catastrophic dimensional breaches. The tithes are maintenance fees. The kingdoms stopped paying because they forgot what the money was for."
Eressia is not a picturesque JRPG landscape. It is a continent suffering from magical decay. The same summoning magic that brought Kaito is also leaking mana radiation, causing crops to mutate and children to be stillborn. The kingdom is not good; it is a desperate polity on the verge of collapse. futaisekai - a tale of unintended fate