Summer Time Machine Blues is based around a group of friends in a science-fiction club who spend their days fooling around at the clubhouse.

The boys play a game of baseball as their friend Yui Ito takes pictures of them nearby.

After the game, the boys return to the clubhouse and head off to the bathhouse leaving the girls, Yui and Haruka to develop their pictures.

They make him explain what happened, but through a series of chain events, Ishimatsu accidentally spills Coke all over the air-conditioner remote control after being hit in the face.

They put Soga on the time machine thinking it is a practical joke on the sci-fi club, but to their surprise it actually works.

The boys decide to travel to the past to steal the remote control before it was broken and bring it back to the present.

While on the tour they encounter their club adviser, Professor Kohtaro Hozumi, referred to as Hose, who explains that changing the past results in the grandfather paradox and would cause the universe to vanish.

Realizing this the remaining club members rush back to ensure that the Ishimatsu, Niimi, and Koizumi do not change the past.

In the process Soga wraps the remote in tape and gets transported to 99 years into the past to prevent the caretaker from discovering the time machine.

When he returns for it he says that it belonged to his mother and Komoto and Ito note that Haruka also possess a similar camera.