Shinchou Yuusha: Kono Yuusha ga Ore Tueee Kuse ni Shinchou Sugiru

Goddess Ristarte is assigned to save an S-ranked world and summons Japanese hero Seiya Ryuuguuin after discovering his absurdly high potential. There is one problem: Seiya trusts absolutely nothing. He buys excessive supplies, trains even after becoming overwhelmingly strong, and refuses to face the weakest monster until every possible risk has been accounted for.

Ristarte constantly mocks his pathological caution, but Gaeabrande soon proves far more dangerous than an ordinary fantasy adventure should be. As irritating and overprepared as Seiya appears, his methods keep saving them from enemies who exploit every mistake. Gradually, Ristarte begins to suspect that his caution is not merely an eccentric personality trait and that there may be a painful reason he fears failure so completely.