The story takes place at the end of the European Middle Ages. The ancient civilization has gradually declined, and people have begun to advocate civil rights.
At the westernmost tip of the Eurasian continent, there is a small island, west of Britain - the Forgotten Land. The royal power of this place is flourishing, mainly due to local historical relics and ancient medieval legends.
People advocated theology, and the order of the knightly race was preserved intact. The people here inherited the abilities of the best heroic spirits in the European Middle Ages through their ancient legends, and founded a kingdom called Algarnia centered on the "Rooftop" with the Lost City as its radiating center. The Lost City has naturally become the economic and educational city of the kingdom. Entering the Lost City is a goal that countless Algarian people have been striving for throughout their lives, because once recognized by the Lost City, they are destined to enjoy Algarnia's aristocratic privileges from this life onwards for generations to come.
However, not everyone can enter the Labyrinth City through hard work. Only those with special abilities, those chosen by God who are born with the ability to inherit destiny, have the opportunity.
On the other side, successfully obtained this opportunity. Entering the maze, how will she deal with the unpredictable future? In her dream, why is there always a person who is always a river away from her...