How a Realist Hero Rebuilt the Kingdom Novel Volume 17 was written by Dojyomaru with illustrations by Fuyuyuki.

After defeating the Gran Chaos Empire, the Great Tiger Kingdom becomes the dominant human nation, splitting the world in two. King Fuuga then extends an offer to his would-be enemy Souma: a joint campaign to the Demon Lord's Domain! Risky as it sounds, Souma recognizes the need to liberate the demon front and accepts. He gathers information on the mysterious demons in earnest, but when their forces go on the march, the demons seem to possess power beyond anything Souma imagined!