"Long ago, our ancestors struck a pact with the gods in exchange for a gift. Thanks to that, life in the frozen lands became somewhat easier. But when sea monsters suddenly appeared, the waters were stained with their black blood, and the land that had been blessed by the gods was torn asunder." Aki, a young boy from a clan capable of manipulating ice, must pass a village ritual to be recognized as a true adult. Though he has failed time and again, he faces the challenge once more, supported by his brother Yako, a skilled hunter. However, Aki had no way of knowing: on this day, his life would change forever.