Summer Time Machine Blues is a story about 5 college boys, Takuma, Masaru, Shunsuke, Atsushi and Daigo, who all belong to a sci-fi club but are not interested in science at all. They usually just hang around, play baseball or cards, or take baths at the public bath.
One day, they accidentally spill Coke on the remote controller of the air-conditioner. In the sweating bath-like clubroom, suddenly a time machine appears. Eventually, they decide to go back to "yesterday" to bring the remote controller. The mission ought to be quite easy, however, gradually they come to be worried. "What if we change the past? Aren't we going to disappear like in movies?"