Space Boy Soran

Dr. Tachibana once designed the highly dangerous antiproton bomb and planned to escape Earth with his wife and children for fear of prosecution. On their way in space, their space ship is almost destroyed and only Dr. Tachibana's children, his son and his daughter, escape. The son is rescued by aliens called the Soran who live on a planet with 15 times the gravity of Earth. They name him Soran after their planet and is turned into a cyborg to save his life. He returns to Earth to search for his sister who escaped, but is yet to be found. He then lives with the archaeologist Dr. Kotsuki and his daughter Mika. and teams up with his pet squirrel, Chappy.

The character of Chappy was believed to be ripped off of a character Osamu Tezuka was creating. In fear of plagiarising, Tezuka's Wonder Three manga had to be serialized in Weekly Shōnen Sunday instead of Weekly Shōnen Magazine, where the Soran manga was serialized. This is actually called the "Wonder Three incident" (W3事件). Chappy appeared to be like the initial design for Bokko, who was supposed to be a squirrel; she was thus changed to a rabbit. Yoshikatsu Miyakoshi was also a former worker for Tezuka. Several members of Mushi Productions were fired or left due to suspicion of industrial espionage.[3]