The girl Tiantian unfortunately drowned while performing the mermaid dance in the aquarium and was rescued by the killer whale Yuyou. Since then, she discovered that she has the super power to understand "whale language".
With the pure desire to send the killer whale back to the sea, Tiantian embarks on an unparalleled fantasy journey in the ocean.
In the process of getting along with her classmate Kazama, she gradually became involved in a huge fetter involving two civilizations.
Can Tiantian send Youyou home? Can mankind find its own path to civilization through the girl Tiantian?
Intention: friendship