A 22nd-century cat-type robot (without ears) who came via time machine to make Nobita happy. He is characterized by a blue body, a round build, a round face with 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 survive safely in any extreme environment (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). He can even light fires in the ocean with an underwater campfire and has an underwater tent for lodging. When flustered, he pulls out useless junk instead of the right gadget.

A 12-year-old boy who is bad at both 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 has a timid personality, cries easily, and is a pathetic, incompetent boy wearing glasses who constantly relies on Doraemon to borrow gadgets. If he takes off his glasses, he actually looks quite handsome.

A 12-year-old girl who is pretty, kind-hearted, and friendly—the quintessential nice girl. She hates fighting. Whenever she sees Gian or Suneo picking on Nobita, she always tries to stop them.

A 12-year-old boy. While not quite at the level of a conglomerate, his family is very wealthy. He is a rich kid who grew up in a grand mansion with parents who dote on him, living a life of luxury that others envy. He is very boastful and arrogant.

A 12-year-old boy. As his nickname 'Gian' (Giant) suggests, he is big, very sturdy, and the best fighter among his peers, earning him the title of the neighborhood bully. Being the local boss, he is self-centered and violent, often occupying an antagonistic position.

An amphibious buggy pulled out by Doraemon to be used as transportation for the underwater camp. Doraemon bought it used at a cheap price. It can travel at high speeds under the sea and has a built-in computer that allows it to speak. Beyond simple conversation, it is curious about humans and asks them questions. These range from standard service questions to simple ones like 'What does friend mean?' and even profound ones like 'Is what is right different from the correct answer?' It is a bit rude and sassy. It can change its size at will and is capable of flight.

A male child soldier and an inhabitant of the underwater Mu Federation. Doraemon's group is unaware of his true identity.