Easygoing Territory Defense by the Optimistic Lord Production Magic Turns a Nameless Village into the Strongest Fortified City (Okiraku Ryoshu no Tanoshii Ryochi Boei Seisan kei Majutsu de Na mo Nakimura o Saikyo no Josai Toshi ni) - Season 1

Van, fourth son of a powerful noble, is just a toddler when he realizes he's been reincarnated. Thanks to his literal lifetime of knowledge, he's raised as a child prodigy until his production magic manifests, and it's the last thing his snooty mage family wants to see. His disappointed father banishes him to a tiny country town on the verge of collapse, yet Van can only see the place's potential. With only his personal maid, past life memories and production magic, can our hero's bastion of battlements build a better life than battle magic ever could?