Saikyou F Rank Boukensha no Kimama na Henkyou Seikatsu?

Lumen, a city on the farthest reaches at the edge of the feared magical borderland. Roy is an new F-ranked adventurer that wandered to Lumen on his own whim. Life on this monster-infested outpost should be a harsh burden for a newbie like him... however, Roy's actually top-class in both swordsmanship and magic?! The sudden appearance of this out-classed "novice" causes havoc in the world, starting in this remote city!

Source: Alpha Manga