While at the beach Arale Norimaki rescues a shark. In return, the shark invites her and the rest of the Norimaki to their underwater city. Meanwhile, Suppaman intends to follow them and get revenge. While in the city, Arale meets Urashima Tarō, who joins Arale while playing at the amusement park.
After a storm hits their island, Yusuke (driving his jet-ski) finds a baby dinosaur. He show it to his dad, they keep it and call it Coo. But there are other parties interested in a 65 million year old creature...
Unable to entertain their princess Puruah, the kingdom of Yapaya requests professor Senbei to create a comedic robot capable of making her laugh for the first time in her life.
