A 22nd-century cat-type robot (without ears) who came via a time machine to make Nobita happy. He is characterized by a blue body and a round physique, with a round face, large white eyes, and a red nose. He pulls secret gadgets out of his 4D pocket. For example, his 'Adaptation Ray' changes the user's physical condition so they can breathe and safely endure any extreme environment (the effect lasts only 24 hours). Other gadgets include the Bamboo Copter (a small propeller worn on the head, not a real helicopter) and the Anywhere Door (a portable portal door). He can also light fires in the sea with an underwater campfire and has an underwater tent for lodging. When flustered, he pulls out useless junk gadgets.

A 12-year-old boy who is bad at studying and sports. He is a coward. Not only is he below average in almost every area, but he was born with incredibly bad luck. He is timid, cries easily, and is a pathetic boy with glasses who relies on Doraemon to borrow gadgets every day. He is a crybaby coward, but he becomes quite handsome when he takes off his glasses.

A 12-year-old girl. She is the typical pretty and kind friend, with a beautiful face, a good heart, and a gentle personality. She hates fighting. Therefore, whenever she sees Gian or Suneo fighting with Nobita, she is always seen trying to stop them.

A 12-year-old boy. His family isn't quite at the conglomerate level, but they are very wealthy. He is a rich young master who has enjoyed an affluent life under parents who adore him, living in a grand mansion. He is very boastful.

A 12-year-old boy. As his name suggests, he is large and very sturdy. He is the neighborhood bully because he is the best fighter among his peers. As the neighborhood boss, he is self-centered and violent, occupying an antagonist-like position.

An amphibious buggy that Doraemon brought out to use as transportation for the undersea camp. Doraemon bought it used at a low price. It can run at high speeds underwater and has a built-in computer so it can talk. Beyond simple conversation, it is curious about humans and asks them questions, ranging from routine service questions to simple ones like 'What does friend mean?' and even profound ones like 'Is what's right different from the correct answer?' It is a bit rude. It can change its size at will and is capable of flight.

A male child soldier and an inhabitant of the undersea Mu Federation. Doraemon's group does not know his true identity.