Ore wa Subete wo "Parry" suru: Gyaku Kanchigai no Sekai Saikyou wa Boukensha no Yume wo Miru

Ever since he was a young boy, Noor has wanted to be like the adventurers in his father's stories—dragon-slayers, curse-breakers, heroes who always save the day. But as everyone knows, to be an adventurer, you've gotta have the right skills! Unfortunately for Noor, his "Parry" is bottom-of-the-barrel useless, his prospects are nonexistent, and everybody he knows is telling him to throw in the towel. Faced with this harsh reality, he figures there's only one thing to do: make up for it with effort! An intense, solitary training regimen ought to do it. If one year won't cut it, he'll train for five! If not five, ten! Now facing the tail end of his twenties with no new skills to show for his labors, Noor sets out to become an adventurer anyway, determined to try one last time to make his dream come true. He might be clueless when it comes to adventuring, but he's no stranger to hard work! Now, if only he can figure out why everyone keeps looking at him like that...

(Source: J-Novel Club)