Summer Time Machine Blues

5 college boys, Takuma, Masaru, Shunsuke, Atsushi and Daigo all belong to sci-fi club, but they are not interested in science at all. They usually just hang around, play baseball or card, or take bath 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?"