Easygoing Territory Defense by the Optimistic Lord: Production Magic Turns a Nameless Village into the Strongest Fortified City (Manga) Vol. 4

Concerned about the progress Van is making with his fortress town, Count Ferdinatto sends his youngest daughter, Arte, and Viscount Panamera as messengers to visit the "child prodigy." Fortunately, Panamera is touched by Van's dedication to his people and proposes an alliance. However, amidst this bright outlook for the future, a new threat descends - a magic beast unlike anything the region has ever seen - and sparks an all-out war!