The 8th Son? Are You Kidding Me? Hachi-nan tte, Sore wa Nai deshou!

Waking up in a new world, 25-year-old Shingo Ichinomiya realizes that he is in the body of a six-year-old. Retaining memories of his stressful life working at a firm company, Shingo learns that the person he is occupying is Wendelin Von Benno Baumeister, the eighth son of a poor noble family living in the countryside. Awoken to his bizarre situation, Wendelin strives to change his financial and social status for the better. His newly discovered great magical aptitude may prove to be just what he needs to achieve that goal. [Written by MAL Rewrite]