Ristarte, a novice Goddess of Healing, is tasked with summoning a hero to save the world of Gaeabrande from a Demon Lord. She picks Seiya Ryūgūin, a Japanese hero who has unusually high stats. She immediately summons him and while he appears to be ideal for the situation, she soon realizes that she forgot to check to see what Seiya's personality was before picking him, which states that he is "impossibly cautious". After seeking advice from fellow goddess Ariadoa, Ristarte decides to leave Seiya alone to train. A week later, he manages to reach level 15 doing only basic exercises...