A young woman named Mimi (Marian) who adores Bankichi Shiraishi (Koji Ishizaka), a magazine photographer aspiring to be a writer, suddenly arrives from the future in a UFO-shaped time machine at his boarding house. She calls him "Grandpa." In the future, "love" is considered a dangerous idea. Mimi comes to investigate her ancestor Bankichi and finds out the name of his future spouse. This is a science fiction comedy about the uproar she causes in modern 20th century society.