In a world consisting of numerous isles, a young hero from the Astora Isle encounters the adventurer Kyle and follows him on an expedition on the isle. They meet a mysterious girl named Iris and a talking white cat, and together they make their way to the isle's ruins, where they find a flying island. Kyle becomes consumed by darkness there, and the party resolves to travel to the ends of the world on the flying island in order to find the seven "Great Runes", following Kyle's words before he disappeared.
Episode 1
The world is split between a kingdom of light in the sky and a kingdom of darkness on earth. As the King of Darkness devotes himself to war, monsters ravage his lands. A boy whose village was destroyed by monsters questions the king's rule.
Episode 2
The monstrous Bahl attacks the Kingdom of White, indiscriminately slaughtering all in his path. While Iris rushes to intercept him, the Prince of Darkness begins his training to become king far below in the Kingdom of Black.
Episode 3
In the Kingdom of White, Iris reflects on her duties and the events that led her to become queen. Meanwhile, in the Kingdom of Black, the Prince of Darkness enters a competition to make his position as heir to the throne official.
Episode 4
The prince and Adel travel as envoys to the Kingdom of White. Although they bring an offer of alliance, their nations are still at war, and they are greeted with suspicion and hostility. Can the prince successfully navigate the pitfalls of diplomacy?
Episode 5
Iris agrees to join forces with the King of Darkness to put an end to Bahl and his indiscriminate rampages. The forces of darkness rally to stop Bahl's assault, but can they hold out long enough for the two monarchs to bring him down?
Episode 6
Groza joins the prince and Adel in the Kingdom of White, bringing an offer to extend the peace between the kingdoms. While the two sides work to build their newfound frienship, Groza finds herself irritated by the prince's interest in Iris.
Episode 7
Iris leads everyone to her kingdom's woods to pick wild greens for a group meal. Over the course of their time together, the two groups gain a new appreciation of their differences and what they can learn from each other.
Episode 8
The prince, Adel and Groza are suddenly recalled to the Kingdom of Black. All seems to be going well during their final audience with Iris until Adel begins acting strangely.
Episode 9
After his return to the Kingdom of Black, the Prince of Darkness is barred from the palace and ordered to hunt dangerous monsters on the frontier. Meanwhile, Phious worries about Iris's condition as the Kingdom of White prepares for war.
Episode 10
Phious hurries to retrieve the Shining Droplets that will heal Iris while the forces of darkness besiege the Kingdom of White. Meanwhile, Groza confronts the Prince of Darkness about her feelings for him.
Episode 11
With the prince and Groza left stranded on the surface, the King of Darkness launches his final assault on the Kingdom of White. Will Iris and her forces be able to withstand his onslaught?
Episode 12
As Iris makes a last, desperate attempt to stop the King of Darkness, the prince finds himself blocked from joining the battle by a familiar face.
