Genjitsu Shugi Yuusha no Oukoku Saikenki

Nineteen-year-old Kazuya Souma expects none of the usual glory when he is summoned to the struggling Kingdom of Elfrieden as a hero. Faced with debt, food shortages, and a state barely holding itself together, he concludes that slaying monsters will solve far less than sound administration. His practical proposals impress the royal family so much that the king unexpectedly hands him the throne and betroths him to Princess Liscia. Suddenly responsible for an entire nation, Kazuya begins gathering talented people from every walk of life and rebuilding Elfrieden through economics, law, agriculture, diplomacy, and whatever other reforms reality demands. In this kingdom, his greatest battles are fought with policy rather than a sword.