High school girl Ruri meets graduate student Nagi while collecting minerals in the mountains.

Ruri is determined to find gold, but Nagi explains that it might not be as likely as she hopes.

Ruri meets Nagi's colleague Imari, and the three embark on a journey to find a lost mine.

In search of sapphire, Nagi teaches Ruri how to study sand, but Ruri prefers to hunt on a bigger scale.

Ruri, Nagi, and Imari head to the beach in search of agate, and Ruri learns about the long lifecycle of rocks.

Just as the group begins searching for sapphire on foot, Ruri uncovers a grave mistake that halts their plans.

Ruri finds sea glass on the beach and runs into her classmate Shoko, who has a secret passion for minerals.