This Pretty Cure group is led by Ariel, the youngest daughter of King Triton and Queen Athena.
Ariel becomes Cure Atlantica when she finds the PreChan Mirror that turns to be extra when accidentally made by magic.
Her sister, Adella, all of a sudden, gets transformed into Cure Serenade and then unexpectedly obtains her very own LovePreBrace.
Aquata becomes Cure Stream when she hugs her soft toy seahorse, Mr. Fuzzyfinkle, crying over what remains of her mother Queen Athena beyond 10 years.
The bubbly Andrina becomes Cure Halibut when she sees all the other sea inhabitants mingling joyfully in Atlantica's intermarine party organized by the mermaid Kiry.