The heat and humidity of the rainy season make it difficult for the DIY club to get any work done, so Kurei invites everyone to her house for air conditioning. When Serufu and the others visit Kurei’s room, they discover a surprising side to her.

The DIY club’s tree house plan is moving ahead. The items they made are selling, so they’ll soon have the money they need. With the club’s input, Serufu draws concept art to base the blueprints on, but no one has drafted anything this big before!

The DIY club suffers a massive shock. Devastated, they head home without beginning the construction of their secret hideout. When Purin hears what happened from Jobko, she digs out an old keepsake and goes to see Serufu.

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.