Nadia: The Secret of Blue Water (Original Japanese)

Paris, 1889. Jean, a young inventor, attends the World Exposition to take part in its flying contest. But when he chances upon Nadia on the bank of the Seine, he is smitten. Jean tries to engage her in conversation, when suddenly the two are chased by a trio who is after Nadia's jewel, the Blue Water.

Having successfully fled from the three villains, Nadia spends the night at Jean's place in Le Havre. But the three return to attack the next morning in the Gratan, their multi-purpose tank. Nadia and Jean jump onto an aircraft Jean created, the Etoile de la Seine VIII, and fly off.

Jean and Nadia make a narrow escape from the trio, but their aircraft breaks down and a battleship rescues the pair. The Gratan still makes the move to attack, but they are no match for a battleship. The relief is short-lived, however, as a mysterious giant sea creature appears.

During battle with the mysterious giant sea creature, Jean and Nadia are thrown overboard. Just then, another giant sea creature appears before them…or is it?

Jean and Nadia bid farewell to the Nautilus and head for France. But they are suddenly shot down, and crash on an island which turns out to be ruled by mysterious invaders.

After their friend Marie is abducted by invaders, Jean and Nadia infiltrate a secret base in the center of the island to try and rescue her. They discover the base was built by an organization who call themselves Neo Atlantis.

Nadia turns herself in to the enemy in order to save Jean. While holding her friends hostage, Gargoyle, the head of Neo Atlantis, pressures Nadia into helping the organization. What is his objective? Meanwhile, Jean heads for the center of the base to rescue them.

Jean is reunited with the Grandis trio and they decide to join forces. Jean marches into the castle and faces Gargoyle. In exchange for Nadia and the hostages' lives, Gargoyle attempts to get him to tell where the Blue Water is.

The Neo Atlantis base collapses and everyone escapes in the Gratan. Sounding an SOS to the Nautilus, they are rescued by Nemo, who cannot hide his surprise at seeing Nadia for the first time.

The Nautilus pursues Gargoyle's airship the Carcharodon, but instead are trapped in the strait, surrounded by the latest in drifting mines. Grandis, who is in love with Nemo, proposes a plan to remove the mines using the newly repaired Gratan.

Grandis and the gang are appointed as apprentice crew. Now a recognized guest, Nadia tries to be of use by helping Grandis in the kitchen but keeps messing up. Meanwhile, Jean wanders into the engine chamber and catches sight of something…

Nemo grants a hunt day and lands Nautilus on an uninhabited island. As the crew stream onto the island, Jean is amazed to see how many have assembled to destroy Neo Atlantis. That night, on the island's beach, Grandis tells Nadia about her past.

Nadia is enraged that a fawn has been hunted for food, which causes her to get into a fight with Jean. Meanwhile, as the crew members busily engage in work, Marie decides to explore the island with King. They get lost and stumble upon the Garfish, which is anchored off the island.

The Nautilus sets off again in pursuit of the Garfish. Just then, Marie is struck by fever and Nadia also collapses. The two are given two days to live and to save them the crew must get a special herb found on the ocean floor.

Though Jean is increasingly mesmerized by the Nautilus's technology, Nadia is repulsed. When the Nautilus is damaged in battle it must surface for repairs but waiting for them is an American fleet and soon an attack has begun.

Nadia is haunted by the conflict caused by the Blue Water. Meanwhile, the Nautilus heads to an underwater ruin to lay some of its crew members to rest. As the crew pay their respects, Jean spots something.

Having learned of his father's death, Jean wants to become a member of the Nautilus' crew in order to avenge him, but Nemo refuses. To cheer him up, Nadia says she wants to fly in his aircraft again, prompting Jean to design a new autogiro.

Running low on supplies, the Nautilus heads for a secret base in Antarctica. However, the ship is trapped by a nautilus, a mollusk that is said to have lived hundreds of millions of years ago. The submarine takes a direct hit as the mollusk’s tentacles tighten their grip.

As Nemo, Jean, and Nadia traverse Antarctica they pass through an ice museum filled with extinct species. Jean and Nadia are astonished at these unfamiliar lifeforms. Then, at their destination, they find Nemo's friend, a whale named lrion.

Gargoyle has constructed a flying battleship and attempts to defeat Nemo. Meanwhile, Jean is immersed in his inventions and creates a miniature jet plane. But when its test flight fails, the explosion causes the Nautilus to be detected by the Garfish.

Gargoyle deploys his new Super Catch Beam against the Nautilus. After being suspended in mid-air and attacked with atomic vibrations, the ship faces dire circumstances. Then, second-in-command, Electra, hatches a plan.

The Nautilus sinks toward the bottom of the ocean. Captain Nemo assembles the crew in the main block and then separates the combat block which self-destructs, destroying the Garfish. Sequestered in the main cabin, Captain Nemo attempts to save Nadia and her friends.

The Captain's cabin slowly makes its way on the sea. Nadia, Jean, Marie, and King are at constant risk of water leaking in, but they finally land on a deserted island. Nadia makes up her mind to live here, where there are no villains, or anyone else

After spending a night on the island Nadia names the inlet and beach and then ventures into the forest to live without science or civilization. Meanwhile, Jean, Marie, and King construct a hut and make other preparations for living on the island.

Jean and Nadia get into a big argument about whether to eat meat, leaving Nadia angry with Jean. But when she gets sick from eating rotten spinach, Jean sets out looking for medicinal herbs and finds a strange mushroom.