Free! Eternal Summer: Kindan no All Hard!

Lalabel is a magical girl who arrives in the Human world to stop an evil wizard from stealing various magical objects or items. As a magical girl, she has a kitty for a companion and a magic wand. Coincidentally, she lands on the doorstep of the Tachibana couple and lives in with them during her stay in the human world. She attends the local school and begins to learn about the different things in the human world. (Source: ANN)

Nanami Simpson is a young girl. Her mother dies when she is young, and she goes to live with her father, Scott Simpson, on board a marine research vessel, the Peperonchino. Her father is a marine biologist, and he is in search of a creature known as the glowing whale. When he finds the bones of one of these, he is saddened, and resolves to change his mission toward preserving and caring for the creatures. Nanami befriends an Orca which she names Tico, and she goes swimming with it every day. Eventually, she learns to breathe underwater which astounds her father. Nanami nearly drowns one day, and one of the glowing whales saves her from certain death and returns her to the vessel, where her father finally gets to see it. (Source: ANN)