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.