The Hero Is Overpowered But Overly Cautious Vol. 1 (manga)

Can a neurotically overprepared hero and an underachieving goddess save a parallel world together?!
When the inexperienced goddess Ristarte is tasked with the daunting mission of saving the S-ranked world Gaeabrande, she thinks that summoning Seiya Ryuuguuin, a Japanese teenager who has utterly broken stats as a Hero, will finally turn her luck around. Seiya's abilities (and good looks) are all she has ever dreamed of, but she soon wishes she had read the fine print about his "overly cautious" personality...