For their next test, the girls are brought to a village of mermaids where they must use their voices to open up some clams. During a break, Mirai and Riko make friends with three young mermaids who show them their village's treasure; a giant clam containing a treasure that allowed mermaids to swim through the sky. Just then, the village is attacked by Gamets and his Clam Yokubal. As Mirai and Riko stay strong in the face of danger, the clams open up in response and awakens the village's treasure, the Linkle Stone Sapphire. Transforming into the Sapphire Style, the Cures are able to use the power of flight to defeat the Yokubal.