The 8th Son? Are You Kidding Me?

A Japanese salaryman falls asleep before waking up and finding himself as a five year old boy named Wendelin von Benno Baumeister, during the wedding of his oldest brother Kurt and his wife Amalie. Despite being nobles, Wendelin discovers the Baumeisters are poor and only owns small farmlands which most of it will be inherit by Kurt while the rest of his six older brothers have either married into another family, finding work as a government official or soldier, leaving him nothing to inherit. Wendelin later discovers he has the ability to use magic. While searching for firewood for his family, Wendelin meets Alfred Rainford, who detected the boy's magic, saving him from a wild boar and vows to teach him how to use magic.