Senbei Norimaki, Penguin Village's goofy scientist, finally finishes creating the perfect humanoid android. Her only flaw is that she is nearsighted and needs to wear glasses. Senbei takes her into town to convince everybody she is a normal 13-year-old girl.
Arale starts her first day at Penguin Village Junior High School. While introducing Arale to the principal Senbei meets Ms. Yamabuki, Arale's new teacher who Senbei falls in love with. While Arale is at school she meets her new friends Akane Kimidori, Peasuke Soramame and Taro Soramame.
All the people who are in the school activity clubs have asked Arale to join them, because she is extremely talented in all kinds of sports. Arale decides to attend all the clubs but, because of her abilities, she starts lots of troubles at the clubs...
Arale comes home from school and tells Senbei that the girls at school said that she is missing a part of the body that the other girls had. Senbei makes a pair of glasses that see through peoples clothes so he can see girls naked and find out what "body part" she was missing.
Senbei gathers Arale and Peasuke to come along to a trip on the Time Slipper to the prehistoric ages to catch a dinosaur. While failing to get a dinosaur they meet Peasuke's prehistoric ancestor who gives them a rare egg in exchange for Senbei's lighter. When they return to the present the egg hatches and a strange angel like baby creature comes from the egg.
After the strange baby hatched from the egg, Arale and Senbei try to raise it. They find out that it eats metal and is powerful after it survives a long fall after Arale threw it to high on accident. Later at night in the bath, Arale and Senbei discover that it has wings. They decide to name it Gadzilla but "Gatchan" for short and then keep it as a member of the family.
Arale has told Senbei that a teacher is coming to their house. Once he hears this, he thinks Ms. Yamabuki is coming, so he has invented a barber machine to groom his hair to look nice. However, this barber machine is a failed robot.
Arale and Gatchan meet a Bank Robber while playing outside. The Bank Robber tries to use them as hostages, but instead becomes fightened at them because Arale didn't get hurt when accidently shooting herself with his gun and Gatchan nibbled a part of his gun when he tried to it as hostage.
Arale's day is a normal day to her, but it is not a normal day for everyone else! In the morning, she destroys a police car, and at the school she eats a bunch of whisky bonbons and gets drunk. That night, she starts having a stomachache.
Donbe plays spiteful pranks on the people of Penguin Village. He runs into trouble after failing to impersonate Miss Yamabuki to get the school's fish and Dr. Slump is mistaken for Donbe. As Donbe finds out how powerful Arale is, he gets his foot caught in a trap and reveals to Arale how badly humans treated him and his parents. Arale invites Donbe over to Dr. Slumps to receive medical treatment despite the trouble the fox caused him.
Arale blabs to Dr. Slump about Miss Yamabuki's strawberry panties. Helped by Arale's animal friends, the professor conducts a complicated scientific process so he can get a peek at Yamabuki's panties. However his attempts fail, leaving him in a state of shock.
The Alien King Nikochan abducts Arale and Gatchan and is intent on destroying the Earth, but Gatchan eats the alien spaceship. While Dr. Slump builds a new spaceship, Nikochan is driven crazy by the positive reactions the inhabitants show towards aliens. The new spaceship is finished but never leaves the Earth.
Dr. Slump is antagonized by a crazy and quick-judging policewoman. The professor finds himself chased by the townspeople when he tries out his invisibility formula, until he sustains full body injuries.
Dr. Slump chastises Arale for her antics. Arale's old acquaintance, Thief-San finds himself dragged into the house, but Arale helps him steal the household inventions, to Slump's chagrin. Still determined to prove that she is a good girl she takes Yamabuki's lesson with such enthusiasm, that she terrifies the animals of Penguin Village and puts the police through a lot of trouble.
Suppaman has appeared at Penguin Village. He thinks he is a super hero, but everyone knows he is a troublemaker. The only thing he can beat Arale and Gatchan in is rock, paper, scissors. However, for some reason Arale starts to admire him.
Arale finds a camera which will show the future. She takes everyone's photo with the camera to see how the future will be 10 years later. All of her friends become 23 years old, but Arale is still the same....
Trampire and a werewolf come to Senbei's house for fresh blood and money. Trampire tries to drink Arale's blood, but it's impossible since Arale is an android. Then, Arale and Gatchan start sleepwalking and scare the two monsters away.
Arale and Gatchan have gone to the world of fairy tales by Wonder machine. In "the Peach Boy" world, she becomes friends with devils and they start playing a game of tag together! Then, Arale starts changing the fairy tale.
Senbei, and Ms. Yamabuki go to outer space. While they are flying in outer space, Senbei wants to go to bathroom, so he decides to land on the closest planet. However, once they land on the planet, Ms. Yamabuki is kidnapped by a monster.
When Senbei returns to Earth, they meet old Akane and Taro. When Senbei tells his name, they don't believe him. Because, according to them, the real Senbei never returned to Earth since he left 50 years ago.
Dr. Slump fits a miniature spy camera in Arale to survey her activities and get a glimpse at Miss Yamabuki's panties. His plan works, but Dr. Slump proceeds to make a video recorder and sends Arale to take a bath with Miss Yamabuki, so he can record a video of Yamabuki's naked body. This does not work out for him with Arale being distracted and Donbe makes Dr. Slump's plan backfire.
Two aliens show up in Penguin Village. They accidentally dropped their child on Earth, so they come to look for their child. Once they see that Gatchan and Poo are playing, they finally find their child.
Recently, a lot of crimes are happening in Penguin Village. One day, Suppaman robs a bank. Polices arrest Suppaman, but he easily breaks out from the jail. A police officer, name Arale, starts chasing Suppaman.
Arale finds out Kinoko wets her bed, so now she wants to wet her own bed. Arale tries to dream about something related to water, but she still cannot wet her bed... So Senbei invents a pillow which will allow her to dream about anything.
Senbei tries to become famous, because he thinks Ms. Yamabuki will like him. So, he invents a Movie Machine to shoot a movie easily. He lets Akane be the producer and he becomes the actor of "The Little Cat Riding Hood".
Arale and Peasuke believe in Santa Claus, but Taro and Akane laugh at them because they think it is so childish to believe in such things. So Senbei decides to become Santa Claus to show Taro and Akane... seeing is believing.
Today's episode of Dr. Slump is extra special! It is a musical of Cinderella! Senbei becomes Cinderella and Arale becomes the witch in this episode! However, it seems like this Cinderella story is something different than the usual Cinderella story..
Arale time slips to "a while ago", and meets Musashi, who is on his way to have a duel with his rival Kojiro. However, somehow Arale and Musashi start doing Rock Paper Scissors, but he refuses to lose to her, so he keeps on battling..
The police officers, Gala and Pagos, meet Arale on the street. For some reason she doesn't destroy their police car as she usually does. They start wondering something is weird about her so they decide to follow her.
Senbei, Arale, and Gatchan have gone to Metropolis Island, because Senbei gets an offer to be on TV. While Senbei is shooting the TV program, Arale and Gatchan start playing war outside of the studio and they start destroying the whole city.
Chivil tries to take Senbei to hell, but Senbei keeps complaining to Chivil that he should go to heaven instead of hell. However, on Chivil's record, there is a proof that Senbei has done something bad in his past..
Senbei makes a promise to Arale to take her to the Amusement Park. However, Senbei also makes a promise to Ms. Yamabuki to take her to a movie on same day! He doesn't want to cancel both, so he invents his copy to keep both promises.
The Can Kicking Contest just started!! Everybody in Penguin Village is very excited because the winner will have whatever he/she dreams of. Senbei tries to win this game because his dream is to marry with Ms. Yamabuki.
Everybody in Penguin Village is talking about the Mysterious Thief Gang. But actually, Arale, Gatchan, and Akane are the thief gang. After they steal Ms. Yamabuki's strawberry pattern underwear, they decide to take Senbei's baked sweet potato.
Anko and Nonko come to Penguin Village for sightseeing from Metropolis Island. However, everybody in the village thinks Anko is Arale, because they look very similar, so they decide to get revenge on her....
Arale and Akane find a weird Takoyaki-ya. Arale never has had Takoyaki before so Akane teaches her "Huff Huff Puff and Eat" technique. Arale loves this technique, So she starts doing "Huff Huff Puff" to all the stuffs in the Village.
A samurai warrior Sugata Sankaku comes to Penguin Village. He is very strong but also he is very hungry. When his hunger reaches an intolerable level, Arale asks him to come to her house to have some of Senbei's ramen.
Senbei invents a miniature house. This miniature house is not a regular miniature house. Whatever happens in the miniature house will become true! So Senbei wants to use this miniature house to make Ms. Yamabuki falls in love to him.