When Ruri has trouble deciding on her future, she turns to her study of sapphire.

Imari leads a hunt for manganese ore, when the group encounters a mystery along abandoned railroad tracks.

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

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

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.

Ruri teams up with Shoko for a science project, which takes a turn when they discover a strange, orange rock.

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

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

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

Ruri and Nagi head out to hunt for opals but discover that the area has already been fully excavated.