When Revenge of Cronos left off, Rom and Leina had crossed a dimensional barrier. Their physical forms changed from robot to human and they were separated with blurred memories. Leina Stol is now incarnated as Leina Haruka, a Japanese schoolgirl. As the story progresses, she meets up with Rod Drill, Blue Jet, Triple Jim, and Rom; all of whom are now human.

A ship crewed by earthlings crashes on Chronos. Believing themselves stranded, the crew volunteers to fight along the Machine Robos.