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.
Man, to think she had something like 
this hidden down there all this time...
Sie muss die ganze Zeit
versteckt worden sein.
Conque escondía algo así.
Conque escondía algo así.
C’était donc ça,
le trésor de ta grand-mère ?
Comunque è assurdo che ci fosse
una cosa del genere nascosta là sotto.
Значит, вот что там было!
แต่ไม่นึกเลยนะว่าจะซ่อนของแบบนี้เอาไว้