Okiraku Ryoushu no Tanoshii Ryouchi Bouei: Seisankei Majutsu de Na mo Naki Mura wo Saikyou no Jousai Toshi ni

お気楽領主の楽しい領地防衛～生産系魔術で名もなき村を最強の城塞都市に～

Van, fourth son of a marquis, 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 podunk town on the verge of collapse, yet Van can only see the place’s potential. Can our hero’s bastion of battlements build a better life than battle magic ever could?!

(Source: Crunchyroll)