During one of the many monster attacks on the city where the story takes place, Silk Koharuno and her two friends attempt to get closer to the monster to get a better view. Unfortunately, the city’s protector, UFO-man, comes to the rescue but inadvertently steps on them and crushes the girls to death. Feeling sorry for what he had done, UFO-man blames their deaths on the monster and promises to bring them back to life by lending them his power. However, now they must become the city’s protectors as well