23 so far and I really like it although married at 10 is crazy. He’s reincarnated in a world with magic as a peasant 3rd son. Farms and creates magic that lets him. Build bricks, walls and buildings, glass, farm, etc. gets land and raises magic beasts but does so well that nobles want to steal it all and attack his little brother- he goes to war, uniting villages and building roads, fortresses and castles. Gains peace after winning and building his lands again as a knight.
I was Reincarnated as a Poor Farmer in a Different World, So I Decided to Make Bricks to Build a Castle.