Level 99 Boukensha ni Yoru Hajimete no Ryouchi Keiei

A high school student is transported to a fantasy world where he becomes a powerful adventurer and saves the land alongside others. After being recognized for his deeds, he is tasked with managing territory under the guidance of a knight named Valtrude. He faces various challenges in restoring a ruined city, dealing with a dwarf town that has stopped producing iron, a port town that evades taxes, and regions overrun by monsters. Alongside his allies, he uses a mix of magic, modern knowledge, and financial tactics to address these issues. After some time, he eventually returns to his original world, only to find himself back a year later.