In the celestial realm, deities oversee countless worlds in need of help; a goddess's task is to summon heroes and aid their quest to defeat the evil in each. Rookie goddess Ristarte, however, has been dealt a terrible hand: she must save Gaeabrande, a world labeled with the S-rank difficulty. While sifting through the hero resumés, she comes across a sheet detailing the abilities of a certain Seiya Ryuuguuin and is astonished by his ridiculously high stats. An elated Ristarte wastes no time in summoning Seiya to the celestial realm, failing to notice the comment on his personality: unbelievably cautious.

Ristarte soon despairs at his bizarre insistence on caution. He has no qualms with unleashing his most powerful ability to vaporize a weak slime, buying out a pharmacy's entire stock of potions, or refusing to do battle unless he is 600% certain of the outcome. However, Seiya's rabid obsession with safety might just be what is needed to save Gaeabrande.