Guin Saga 5: The Marches King is written by Kaoru Kurimoto.

Guin has found the Lagon, but now he must best their mightiest warrior if he is to have any chance of acquiring the giants' aid. Meanwhile, the tenuous Sem alliance has become unglued, leaving them exposed to the Mongauli scouts, who quickly report their location to Lady Amnelis. Now, it is the Mongauli army's turn to trap the Sem. Guin must return with help in time to save his friends.