The 8th son? Are you kidding me?

Shingo Ichinomiya, a 25-year-old office worker, finds himself in the body of Wendelin Von Benno Baumeister, the eighth son of a poor noble family in the countryside. Wendelin, who is six years old, possesses a great magical aptitude, which he uses to improve his family's financial and social status. Shingo retains his memories of his stressful corporate life and guides Wendelin in his efforts to change their circumstances.