Ore wa Teppeiおれは鉄兵; I'm Teppei!; My Name is Teppei!

From Devious Breezes: Uesugi Teppei and his father lives deep in the forest in search of a buried treasure. Isolated from society, Teppei became a wild child with no restaints until one day his uncle found him. Teppei finds out that he is actually from a very prestigious family with 5 siblings. For the first time in his life, he will have to attend school and live under his grandmother's rules. Can Teppei really adapt to his new environment? It was also adapted into an anime that aired from September 12, 1977 to March 27, 1978.