|The Marine Mermaid's Light|
|Air Date||June 19, 2004|
|Previous episode:||Next episode:|
|Her Brother's Feelings||His Secret|
The Marine Mermaid's Light is the 64 episode of the series and the 12 episode of Mermaid Melody Pichi Pichi Pitch Pure.
Coco invites Lucia, Hanon and Rina to come with her to the Indian Ocean to help search for the Legendary Spiral Shell. It turns out to be Sara's shell that held all her memories and the four Mermaid Princesses and Hippo battle the Black Beauty Sisters for it.
In the South Pacific Ocean Castle, Coco was having a dream that she was in the Indian Ocean and Sara's shell was saying "gloom, hopeless, it's all an illusion". Coco wakes up from her dream and swam to the Indian Ocean but she couldn't find the shell. Coco needed help but she could not tell about the shell because she is loyal to Sara.
So Coco went to the Pearl Piari and was seen by Lucia, Hanon, and Rina who just came home from school and was happy to see her again. Coco asked them if they wanted to go treasure hunting in the Ocean to look for the Legendary Spiral Shell that will bring wonderful happenings to anyone who finds it. The girls and Hippo agreed to go.
In the ocean, Coco is swimming faster that normal which made Lucia suspicious. Lucia then heard Seira saying "Someone hurry and find it. Please, someone find it quickly". The Mermaid Princess then picked up their speed to catch up with Coco but forgot Hippo and left him behind. Hippo then used a minteray to catch up as well but it was going in the wrong direction. In the Indian Ocean, the Black Beauty Sisters were hanging out and suddenly found Sara's shell. They were intrigued by its dark energy.
The Mermaid Princesses realize that Hippo is not with them but they thought that he will come back soon. The Blak Beauty Sisters tested the shell's power on Hippo by creating a "swirl of hatred", he swam faster to get away from the swirling hatred.
Coco showed the place where the shell can be hidden and Rina knew that they were not in the South Pacific Ocean but the Indian Ocean. Coco explained that the area they were in is also called the "Graveyard of the Sea". The princesses spilt up to find the shell but have no luck finding it. Lucia noticed something was wrong with Coco and asked why she was worried. Before Coco could answer, Hippo came back screaming. Hippo told Lucia that a black vortex is following him and it was uttering evil chants. Coco figured it out before all the fish swam away in the same direction. The vortex surrounded Coco, Lucia, Hippo, Hanon, and Rina.
The Black Beauty Sisters appeared holding Sara's shell, causing the mermaid princesses wonder how they got it. They used the shell's power to attack the Mermaid Princesses. Hippo transformed into Hippocampus to try to protect them.
Lucia asked Coco to explain because what she said about the spiral shell was a lie. Coco aplogized for deciving them and told them the truth. Hippo was then overwhemed by the power and was reverted back into his peguin form. The Black Beauty Sisters then sang their song toweaken the Mermaid Princesses.
Before Sheshe and Mimi could finish singing, Sara's shell played Tarou's piano song letting the Mermaid Princess have their chance to sing their song. The sisters retreated and the shell slowing floated to Coco who held it in her hands. The mermaid princesses then saw Seira in the shell. She thanked the princesses for finding the shell, thus allowing Sara's heart to rest in peace. She also revealed to be the one who gave Coco those dreams and thanked the princess once again before disappearing.