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Anime / Doraemon: Nobita and the Castle of the Undersea Devil

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The installment of Doraemon's Long Tales which takes place Under the Sea.

Doraemon: Nobita and the Castle of the Undersea Devil is the fourth installment of Doraemon's Long Tales, and also the fourth Doraemon film. Directed by Tsutomu Shibayama, the film was released on March 12, 1983 in Japan.

It's an excruciatingly hot summer in Japan again, and once more the gang's up for an adventure. What started off as a summer outing in the Pacific turns into an excursion into the Bermuda Triangle when an ancient shipwreck is discovered, with Nobita and friends itching to explore the wreck. With their new gadget, the sentient underwater vehicle called Buggy, the gang ends in the depths of the Pacific's deepest trench, where they encounter colossal giant squids, fire-breathing mechanical fishes, and enters an underwater kingdom known as Mu who being invaded by hostile robots from Atlantis.

Doraemon: Nobita And The Castle Of The Undersea Devil contains examples of:

  • Adaptation Dye-Job: The new character and the gang's new friend, Eru, has blond hair in the anime film. In the manga his hair is black.
  • A.I. Is a Crapshoot: Poseidon and his armies took a mind of their own and wiped out their creators, the inhabitants of Atlantis. They are now at war with Mu, another underwater kingdom, are responsible for the disappearance and destruction of various ships in the Bermuda Triangle in the past several decades, and wants to invade the surface world next.
  • Almost Out of Oxygen: This fate befalls Suneo and Gian when they hitched a ride in Buggy towards the shipwreck without informing Doraemon, much to Doraemon's horror. They'll need to re-apply the Adaptational Light in order to survive underwater, and they're less than hour away before the light's effect wears off. Doraemon, Nobita and Shizuka races off to find Suneo and Gian, and barely made it on time before they drown. It turns out it was a passing Mu ship which saved them by re-applying their own Adaptational Light on the unconscious Suneo and Gian before Doraemon's arrival, only for the Mu rescuers to be suddenly attacked by Poseidon's forces.
  • Animal Mecha: Poseidon's army has giant fish mecha the size of ships in it's ranks, which fuels past legends of giant sea monsters.
  • Attack of the Monster Appendage: The gang have to hide from a giant squid inside Doraemon's compact tent, only for the squid to smash a window and stick a tentacle in, with a lengthy scene having the gang trying to fend off said tentacle.
  • Awesome Underwater World: The ocean floor is depicted as beautiful, vibrant, full of life, with assorted colorful underwater fauna. Unfortunately, there's also giant squids.
  • The Bermuda Triangle: Majority of the adventure takes place here, after the discovery of an ancient sunken ship worth 1 billion dollars, which inspires Doraemon and friends to travel underneath the Atlantic for an exploration. It's also here where they discover Mu, an underwater kingdom, and the centuries-old threat which is Poseidon.
  • Big Bad: Poseidon, leader of an apocalyptic underwater army who is the reason behind the destruction of various ships in the Bermuda Triangle for the past decades, and with intentions of ruling over Mu and the surface world.
  • A Day in the Limelight: Come think of it, Shizuka is pretty much the most important character this time round. She gets plenty of moments interacting with Buggy, stopped Doraemon from deactivating Buggy when the gang blames it for nearly letting Suneo and Gian die, and her tears literally saved the world at the end.
  • Because You Were Nice to Me: Buggy considers Shizuka to be his only real friend, compared to Doraemon or the boys, because besides thanking him for being their transport, she also had conversations with it and thanks it for carrying them around (unlike the boys who tends to play rough). This turns out being the catalyst for Buggy's Heroic Sacrifice towards the end.
  • Eat Me: Part of Buggy's Heroic Sacrifice. Realizing that Shizuka is upset and crying, an angry Buggy leaps out of Doraemon's pocket and starts making a beeline towards Poseidon. One of Poseidon's mooks fires a shot that damages Buggy, but prior to it's self-destruction, Buggy managed to force itself into Poseidon's mouth. BOOM.
  • Fantastic Racism: Despite allowing Doraemon and gang to stay in their kingdom, the Mu denizens aren't welcoming the surface folk, to say the least. Gian and Suneo gets shoved instantly into a dungeon after their computers detected them to be a bully and a liar, for starters (they're Loving Bully at worst in cannon) and while Doraemon, Nobita and Shizuka can stay in Eru's quarters and granted access to any facilities they want, they're forbidden to leave, making the whole place seem more like a Gilded Cage.
  • Fish People: Poseidon's foot soldiers are a mechanized version of this trope, being mechanical fish-men.
  • Giant Squid: The gang gets assaulted by a giant squid while underwater, having their camp destroyed in the process. Earlier on Nobita catches a glimpse of the monster's tentacles while they're travelling on Buggy, but nobody really believes him.
  • Ill-Timed Sneeze: As the gang attempts infiltrating Poseidon's quarters via an underground transportation device, a sudden sneeze from Gian draws several of Poseidon's minions towards them. Doraemon gets them out of their predicament with his tunneling mole.
  • Keystone Army: After Buggy sacrifices itself to destroy Poseidon, Shizuka and Doraemon (regaining consciousness) quickly escapes the throne room, only to run into a wave of reinforcements. But to their surprise, those mechanical minions are frozen in place, since with Poseidon's death, they're rendered back to being motionless. Cue Shizuka and Doraemon releasing their friends from the dungeon and escaping.
  • Lost Technology: Poseidon and his robotic army used to be the creations of an underwater race in Atlantis several millennia ago. They wiped out their creators and are now a sentient, self-sustaining race of robots living beneath the ocean.
  • Ocular Gushers: Doraemon's reaction after hearing that Suneo and Gian supposedly died, and blaming himself for taking them on a dangerous underwater adventure. Again, they're underwater.
  • Oh, Crap!: For an almighty underwater robot god, Poseidon gets a really nice one when he sees Buggy, on fire after being shot by one of his mooks and about to explode, coming at him.
  • Peekaboo Corpse: When exploring an underwater shipwreck, Gian and Suneo gets unintentionally scared by a motionless skeleton of the ship's Captain, still seated on the spot since the ship's sinking centuries ago.
  • Prongs of Poseidon: Poseidon's army of Mecha-Mooks uses tridents as their main weapons.
  • Rummage Fail: Another repeated Running Gag from the comics get carried over here, this time being Doraemon panicking while everyone's being attacked by the giant squid, pulling out assorted junk after another. He managed to get the Momotaro Capsules... only to have the squid's tentacle knock it off his hands.
  • Sentient Vehicle: Buggy, the sentient, underwater automobile which serves to transport Doraemon and friends around the Atlantic Floor. It's also a borderline Deadpan Snarker to the boys.
  • Storming the Castle: The story's final battle, which has Doraemon and friends (sans Shizuka due to being used to lure away Poseidon's guards) launching an all-out assault on Poseidon's base with their gadgets and weapons.
  • Swiss-Army Tears: In the story's Darkest Hour, when all the other heroes are captured and taken alive by Poseidon's army, save for Doraemon who made it to Poseidon's throne room... before falling unconscious, Shizuka, upon realizing the hopelessness of the situation, begins crying upon Doraemon. But then, her tears falling on Doraemon's pockets ends up summoning Buggy.
  • Taking You with Me: Attempted by Doraemon; being the only one of the gang to escape capture and make it to Poseidon's throne room, Doraemon tries to finish off Poseidon with a grenade... only to stumble and pass out, much to Poseidon's amusement. Buggy on the other hand...
  • Throne Room Throwdown: A really, really short example of this trope. Doraemon, the only member of the gang not yet captured by Poseidon's forces, made his way to Poseidon's throne room, intending to destroy him... and passes out. A few seconds later, a crying Shizuka unintentionally summons Buggy from Doraemon's pockets, who then pulls a Heroic Sacrifice to destroy Poseidon.
  • Under the Sea: The entirety of this story takes place in the floor of the Pacific ocean. Lampshaded when Shizuka asks when are they taking their baths; Doraemon reminds her they're underwater.
  • Underwater City: Two of these shows up in the story. The first being the benevolent, high-tech city of Mu, whose inhabitants are peaceful, and their prince Eru easily befriending Nobita and friends after rescuing them from Poseidon's forces; the second being Atlantis, a destroyed ancient city whose inhabitants are wiped out by their robots who now rules with the mechanical AI called Poseidon as their leader, who constantly launches invasions on Mu and other peaceful underwater nations.
  • Water Is Air: Doraemon and friends have an "underwater" barbecue. Justified as it's one of Doraemon's many gadgets. Suneo even comments how nice it smells, despite being underwater, but again it's Doraemon.
  • We Need a Distraction: When Doraemon and friends attempts to infiltrate Poseidon's underwater fortress, they decide to have one of them lure out the guards so they can enter without raising any alarms. Shizuka volunteers herself for the task (as she wouldn't be partaking in any violence, unlike the boys) - cue Shizuka walking in the open with Doraemon's mini-band playing loud music, drawing out Poseidon's guards.
  • You Have to Believe Me!: Nobita's attempts to convince the gang that he saw a collosal squid stalking them ends up as this. And later on, he tried telling everyone he saw a giant fire-breathing fish the size of a football field, which predictably ends with him being ridiculed.