In the near future, much of the world has been forgotten at the bottom of the ocean due to rising sea levels. Natsuki Ikaruga, who lives in a small town surrounded and stranded by the sea, is invited by a mysterious woman, Catherine, to search for a treasure in his grandmother's house who was a marine geologist. One day, he dives to the bottom of the ocean in a submarine and encounters a mysterious capsule with a girl sleeping inside. The girl was a humanoid so sophisticated that she could be mistaken for a human.
Are we going on a walk, Master?
هل سنتمشّى يا سيّدي؟
Machen wir einen
Spaziergang, Meister?
On va se balader, maître ?
Padrone, andiamo a fare una passeggiata?
Nós vamos passear, mestre?