- The 20th World Martial Arts Tournament is held on May 7.
- On May 17, The Penguin Village scientist, Senbei Norimaki finishes creating the first perfectly working Android and names her Arale Norimaki and is successfully introduced to Aoi Kimidori without her knowing it's an android.
- On May 18, Arale is enrolled in Penguin Village Middle School in Midori Yamabuki's class and befriends Akane Kimidori, Peasuke Soramame and Taro Soramame.
- On a Sunday, Senbei finishes the first successfully working Time Machine known as the Time Slipper. Some day afterwards, Senbei, Arale and Peasuke use it to travel back to prehistoric times and return with a mysterious egg that hatches and Gatchan is born from it.
- Bubibinman comes to Earth.
- The Moon is destroyed for the first time when Arale throws a rock at it live on Television for a broadcast by the Penguin News Network.
- Arale befriends the fox Donbe, somewhere around this time the Moon is restored.
- King Nikochan and his assistant destroy Mars with their ship, but Gatchan ends up eating their ship, stranding both of the Nikos on Earth.
- Manure-Boy is born.
- ↑ Dr. Slump volume 4 extra, "Dr. Slump Ho-yo-yo Resume"
- ↑ Dr. Slump chapter 2, "Here Comes Arale!"
- ↑ Dr. Slump chapter 10, "The Time Slipper"
- ↑ Dr. Slump chapter 11, "The Mysterious Egg"
- ↑ Dr. Slump chapter 16, "The Invader from Space"
- ↑ Dr. Slump chapter 23, "Barber Shop Panic: Part 2"
- ↑ Dr. Slump chapter 26, "The Story of Donbe"
- ↑ Dr. Slump chapter 29, "Earth S.O.S.!: Part 1"
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