Mushoku no Eiyuu: Betsu ni Skill Nanka Iranakatta n da ga / 無職の英雄 別にスキルなんか要らなかったんだが

In a ritual, the Goddess bestows upon 10-year-old children a "class" that shapes their entire future. As the son of the legendary Sword Princess Fara and Archmage Leon—two of the highest-ranked individuals in their respective classes—Arel seemed destined for greatness. Unfortunately, he is branded as classless and thus unable to naturally inherit any kind of specific skill. However, Arel soon discovers that he can replicate the abilities of any class he desires—though doing so demands significantly more effort than it does for the naturally gifted. Eager to test his unprecedented skills even more by finding stronger opponents, Arel sets out to defy the limits imposed upon him and prove that perseverance can surpass even divinely appointed talent. ...