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.
I do indeed belong to the group of 
precision instruments that you humans
أنتمي بالفعل لمجموعة من الآلات الدّقيقة
الّتي تُشيرون إليها
Ich gehöre zwar zu den von euch Menschen
so genannten Präzisionsmaschinen,
Pertenezco a la maquinaria de precisión
que llaman por ese nombre,
Pertenezco a la maquinaria de precisión
que llamáis por ese nombre,
Je fais partie des appareils automatiques
que les humains nomment ainsi,
Rientro fra le macchine di precisione
 che voialtri chiamate a quel modo,
De fato, eu pertenço ao grupo de máquinas
Действительно, я высокотехнологичное
устройство, которое люди так назвали.