Hortensia Saga is set in the kingdom of Hortensia, a nation that has known peace for some 700 hundred years as a result of being protected from invasion by the tributary states of Olivier and Camellia. However, on the fifth day of the 12th month in the year 767 of the King's Calendar, Camellia erupts into violent rebellion and monstrous demons appear, and the kingdom of Hortensia is plunged into a whirlpool of war. The story follows a group of young knights whose fates are caught up in the tragic conflict.