One morning, on her way to school, carefree, daydreaming Yua Serufu wrecks her bike and an upperclassman comes to her rescue—a chance encounter which sends her down a path to answer the question, "What does 'DIY' mean?"

The DIY club needs more members to stay open. As Serufu wonders just how to do that, her classmate Hikage Takumi offers a thought—“If you made the club room cuter, then maybe other students would take an interest…?”

A genius exchange student from America has surprisingly enrolled at Gata Girl’s instead of YuuVoc. One day, Serufu and the others find her sobbing behind the club room. When she finds out that they’re the DIY club, she starts badmouthing DIY.

Kouki Kokoro, who says to call her Shii, suddenly drops in on the DIY club and asks if she can join. Everyone except Kurei happily accepts her. When Shii says she’ll be helpful because she’s stronger than anyone there, Kurei challenges her to prove it.

The DIY club decides to go to the beach. They’ll gather materials to make little things like bracelets to sell, adding to their club funds. When Purin hears that Jobko is going to the beach, she decides to go along, unaware that it’s a DIY club activity.

Finally, construction on the secret hideout begins! When Serufu invites Purin to build it with them, Purin’s secret is revealed. Together, the club members work through rainy days and sunny ones while their summer vacation deadline draws nearer.

The DIY club holds a celebration at their newly completed secret hideout. Then summer vacation starts and Jobko heads home, promising she’ll see everyone again. Purin takes Serufu to the DIY club, saying that the secret base is still missing something.