Riri's day at a frog-themed amusement park takes a bizarre turn when she pulls a sword from inside the Frog Castle. A mysterious proclamation follows: defeat the giant snake, and the Frog King will grant her wish. She does exactly that, winning passage into the Frog Land itself. There, she meets the Frog King, who presents her with an impossible condition. She'll transform into a frog unless she can open the Gate of Hope before a child hatches from mysterious roe sitting before her. The clock is ticking. Then a suited man named Knodo appears, claiming he's her new little brother. Riri finds this claim deeply suspicious and bolts. Knodo gives chase. Their frantic game of tag ends predictably: both tumble headfirst into the water. The result is a one-episode special that mixes comedy, adventure and the supernatural.