Kisa was a dolphin befriended by Planeteer Gi before she became a Planeteer.
Years before joining the Planeteers, Gi's parents worked as marine biologists until a company called Sternkill Industries bought the land and their grants were revoked. Gi promised Kisa that she would return one day before she left. It took her nearly a year, but Gi was able to return, but found Kisa dying from ocean pollution.
From then on, Gi swore to protect the ocean life.