Deep in the folds of the Airiya Mountains, "Mist Valley" has always been a forbidden legend. Shadow creatures that devour light, rivers that make stones weep, and silver-armored knights who vanish into the fog have kept the villagers' fears fixed on the valley's edge.
But the boy Kyle is fascinated by the mist. After his parents died young, he went to live with his taciturn great-uncle, an old hunter. His only comfort was collecting strangely shaped stones from the mountains. When a fisherman from the village tried to find "treasure" in the valley and returned unconscious, leaving behind a dark silver shard covered in strange runes, Kyle's life was changed forever.
The shard glows, drives away shadows, and even whispers ancient rhythms in his ear. To save the fisherman and solve the mystery, Kyle takes the shard into Mist Valley, only to become caught up in a secret reaching back to antiquity. The valley was once the site of an ancient kingdom that wielded the power of runes. The shard is the key to unlocking a seal, and the valley's strange phenomena are all caused by the uncontrolled power left behind after the kingdom's destruction.
With the brave girl Lina at his side, Kyle encounters shapeless shadows and corrupted Rockclaw Beasts in the mist. They discover a mysterious stone gate beneath an underground river and a temple covered in runes. As more shards merge with his, Kyle gradually learns to read the runes. He discovers the story of how greed destroyed the kingdom, and comes to understand his mission as the "Rune Heir": to reinforce the seal and stop the uncontrolled power from spreading.
When the final rune lights up on the stone tablet, the mist clears and the valley reveals its lush green landscape. Kyle holds the shard, now fused with the Rune Codex, and knows that the adventure is over, but the story of protecting the valley has only just begun. This is a tale of courage and responsibility
