I'm Natsuumi Manatsu! I'm starting my first year in middle school in the city in Spring!
The day I moved to Aozora City, I discovered a secret in the ocean.
This secret goes by the name of "Laura", and she's actually...a mermaid!

In the ocean, there's a land of mermaids called "Grand Ocean",
however, a "Witch of Delays" who lives in the darkest depths of the ocean, deprived Grand Ocean of its "motivation power".
So now no one in Grand Ocean is feeling motivated anymore. I've become Cure Summer!