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!

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.