Dads Day celebrations are coming up at school, but Yuna believes that her father, who is still away and busy with his research on sea slugs, will not show up. Stitch arranges to have Yuna's father arrive on the island and meets him on his ship. Meanwhile, Hämsterviel decides to use a climate-changing machine under the water near the island to cause a powerful storm so that he and Gantu can steal the Spiritual Stone unopposed. Discovering Hämsterviel's machine, Yuna's father and Stitch take a submarine to destroy the machine and save the ocean. In the end, Yuna finally reunites with her father, just in time for Dads Day.

Experiment 303, Amnesio, comes to the island and starts taking peoples' memories.