The school is on a trip to the beach. Unbeknownst to them, the area is infested with one-eyed jellyfish, and Riiya and Shiine get stung. The only hope to save them is an herb from down the coast, but the inlet where the herb is found is guarded by a horrible monster. Chacha, Orin, Marin, and Mr. Rascal go to the inlet to get the herb, but they are discovered by the monster, who turns out to be Umibōko, the younger sister of Umibōzu, Marin's would-be boyfriend. She is out for revenge on Marin for rejecting Umibōzu, but Marin disappeared into the cave while the monster was preoccupied with the others. After she gathers the herb, Marin heads back to find Riiya, but the monster notices her and attacks, causing her to drop all of the herbs into the ocean. Just as Umibōko is about to kill both Chacha and Marin, Umibōzu appears and convinces his sister to leave them alone and leave with him. This does not please the one-eyed jellyfish, who merge into the Evil King Jellyfish and begin attacking Chacha and her friends. Marin gets knocked into the water and finds one of the herbs. Just as Chacha is about to be electrocuted by the Evil King Jellyfish, Shiine and Riiya receive the herb and are cured. Chacha then defeats the Evil King Jellyfish and the episode ends with Chacha and her friends singing by the ocean. (Source: Wikipedia)

Aired on: 4/21/1994