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.

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.