Unexpectedly, humanity faces the sudden rise in ocean levels.
All kinds of disasters occur around the world because of this, and among the victims is Natsuki, who ends up losing his mother, and a leg when a wall falls down.
Years later, the only assets left to Natsuki are an old boat and a submarine that her grandmother, an oceanographer, used in her research.
But also, to his misfortune, he also inherited her debts, and Catherine, a debt collector, never stops reminding him.
One day, Catherine comes to him with a proposition. They say that in her grandmother’s laboratory, now submerged in the sea, there could be a treasure, which could get them both out of trouble.
Catherine convinces Natsuki to use the submarine and try to find the treasure, and although Minamo, one of his childhood friends, opposes it, she also ends up helping them on their expedition.
Natsuki is still suffering from the psychological disorders of the tragedy, but he still submerges the submarine in the ocean.
Once in his grandmother’s laboratory, Natsuki discovers a capsule, and inside it he sees the body of a girl.
As he approaches, the movement activates something and suddenly the girl opens her eyes, surprising Natsuki, who makes a sudden movement and ends up trapped, while remembering when he lost his leg.
Surprisingly, the girl swims towards him and helps him recover the submarine to ascend to the surface.
Atri, as she calls herself, is a robot programmed by his relatives. For Catherine it is an easy opportunity to make money, but for Natsuki it could be more than a memory.
(アニメ)