"The Galactic Patrolman Goes to Earth" (銀河パトロール地球へ Ginga Patorōru Chikyū e) is the first chapter of Jaco the Galactic Patrolman.
Tokunoshin Omori narrates the story the beginning of the story saying that he is a scientist who was never really interested in space and how he encountered an alien ten years ago. A spaceship that is heading towards the Earth ends up crashes against the Moon and falls to Earth. Down on Earth on Omori's Island, he is seen giving up on working on his Time Machine for the day and then bringing some flowers to his wife's grave. As night falls, he is seen in his house eating dinner and watching the news where they are interviewing the idol An Azuki about her boarding the rocket known as the Twinkle 8 in three days. Omori turns the television off in annoyance and decides to read outside and smoke a cigarette where he then sees the falling spaceship which he thinks is a Plane land in the ocean right in front of his island.
Omori quickly heads to the dock worrying about the pilot and says that since its dark he can't use his Boat because of the Monster Shark. As Omori sees the Monster Shark's fin rise up, the spaceship is seen moving towards the shore as the pilot ended up pushing it to shore by swimming. The pilot is shown to be an alien and lifts the ship right out of the water and throws it onto the dock. Omori questions the alien believing that he is just a foreigner with a weird plane but he reveals himself to be a super elite member of the Galactic Patrol. Omori tells the galactic patrolman that he wants him off of his island since he hates people which he responds by saying he can't since his ship is broken. He says that he bumped into the moon because he was watching a video on his ship and now he can't even call his comrades for help.
Omori promises that he will try to fix it in the morning, but expresses doubt that he can actually fix it. He lets the alien stay at his house, and offers the alien food, but the alien explains that he can only drink and eat milk and cheese. He reveals that scout robots were sent to Earth since the ancient times to gain information and that in every hundred-thousand flies is a scout robot of the galactic patrol. He also reveals that he has all the languages of the universe inputted into his brain. However, he got lazy and skipped the session about repairing the session about repairing the spaceship. The man inquires whether the aliens have time machines, and the alien responds that they do not, because time travel is dangerous and is forbidden by the Intergalactic law. Omori formally introduces himself, while the alien reveals his name is Jaco.
While Omori is asleep, Jaco dives into the ocean and confronts the Monster Shark. The giant shark attacks it but Jaco dodges and kills it. When Omori wakes up, he finds Jaco watching TV. Jaco replies that it only needed to sleep for 30 minutes. It tells Omori that it killed the Monster Shark. Omori thinks it's joking at first, but when he looks out at the sea, he sees the Monster Shark dead. Jaco says that he is now indebted to it. They chat about the news, which featured An Azuki who was going to go into space with no training, so that the space agency could gain money.
They reach the house, and then Jaco points out to a collapsed building. Omori reveals his past; he created theories about creating a time machine and the government decided to fund his research to create the machine in secrecy on the island. As the chief supervisor of the project, he lived with his wife on the island. But one day, an assistant made a mistake with the management of the high-prressure gas, and there was a huge incident, leaving many people dead. Omori was only injured, but his wife also died in the accident. The research and island were abandoned due to the incident, but he decided to stay with his wife's grave. He believed the government was going to use it for no good, and reminded him that the Earth had too many evil people. He analyzes the damage and infers that an important part of the engine has been slightly damaged. Jaco shows disappointment in the human race. It explains that the radar system at their headquarters detected a projectile leaving a planet of dangerous aliens. When they calculated it's route and speed, they found out it would reach around the island in three days at 10:00 A.M. A fearsome alien is on the projectile, and it says that it is its duty to defeat the alien.
Due to the difficulty of the task at hand, Jaco offers to use an Extinction Bomb to wipe out only humans from the Earth. Omori persuades Jaco not to use the bomb, and Jaco agrees, but threatens to activate it if he's annoyed.