Easygoing Territory Defense By The Optimistic Lord: Production Magic Turns A Nameless Village Into The Strongest Fortified City (Manga) Vol. 1

In this fantasy isekai tale, a reincarnated nobleman with a "useless" skill transforms a village into a prosperous city! Van, the fourth son of a powerful noble, is only two years old when he remembers his past life as a salaryman in Japan. With his adult brain in a young body, he's considered a child prodigy... until he displays the "Production Magic" skill when he turns eight. In a family that favors offensive magic, this crafting skill is considered useless in battle, and Van is banished to oversee a tiny country town in disgrace. With only his personal maid, his father's butler, a knight, a rescued slave, the memories of his past life, and his "worthless" magic, can Van improve the fortunes of this little village-and himself?