The 8th Son? Are You Kidding Me?

Synopsis (en anglais)

Ichinomiya Shingo, a 25-year-old man working at a firm company, while thinking of tomorrow's busy working day, goes to sleep. However, when he woke up, he found himself in a room unknown to him and realized that he is inside a 6-years-old body, taking over his body and mind. He soon learns from the memories of the boy that the boy was born as the youngest child of a poor noble family living in a back country. Having no administrative skill, he can't do anything to manage the vast land his family has. Fortunately, he is blessed with a very rare talent, the talent of magic. Unfortunately, while his talent could bring prosperity to his family, in his situation it only brought disaster. This is the story of the boy, Wendelin Von Benno Baumeister, opening his own path in a harsh world. (Source: Crunchyroll)