Yuri Shibuya is flushed down a toilet into an alternate world where he finds out he is now the king.

While attending a dinner party, Yuri meets more of his subjects and accidentally challenges Conrart's brother, Wolfram, to a duel.

Yuri convinces Wolfram to take him out to help protect a human refugee village; Yuri decides to become the demon king and attends his coronation ceremony.

Back on Earth, Yuri decides to start his own baseball team; Günter and Gwendal want Yuri to hunt down the demon sword, Morgif.

Pirates attack after Yuri, Conrad and Wolfram set sail for an island where the demon sword, Morgif, is rumored to be located.

After reaching the island and learning about a legend of a cursed hot spring in the mountains, Conrad, Wolfram, Yuri and Jozak decide that is where Morgif will probably be found.