"In this land, there is no King without the Hero. Without the King, the Hero has no purpose."

On a seemingly random day, Eli Richards is transported to another world. The small but rich land of Evangel is riddled with monsters and Bosses; the haven being the single Castle Town filled with spirited away villagers.

Lost of his memories of his family and hometown, he is thrusted with a sudden purpose to become the Hero of Evangel and help the young Atreo become King. Along the way, he meets many people that will help him defeat the three Boss Monsters to achieve his goal.

One of them is a Boss Monster herself... Bahamut.