Zeo, a mysterious young wizard with a giant sword, finds himself in the city of Monea. He has no interest in getting involved with other adventurers, but circumstances leave him no choice but to find himself a party. He is therefore dragged into a group of misfit adventurers led by the pretty priest Tia.

Tia seems very interested in making him their ally, and he soon learns why. Tia is determined to hunt down the sorcerer and summoned demon that destroyed her town and family, and she intends to do this by first summoning the demon. However, demon summoning magic is forbidden, punishable by death. Tia needs to learn about the art of demon summoning, and she needs a wizard for the summoning itself. Little does she know, Zeo actually has his very own illegal summoned demon, which is why he was so insistent that he wanted to adventure alone. Will he be willing to help Tia with her quest, or will his secret lead to his execution?