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…?”

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.

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.