Medaka Mermaid Quintuplets

The Medaka Mermaid Quintuplets are five tiny young mermaids who are friends with Keimi. Their names are Ichika, Nika, Sanka, Yonka, and Yonka Two.

Appearance
The Medaka Mermaid Quintuplets are five tiny identical-looking mermaids. They all have curly hair and tails with white stripes. They also all wear cowboy hats, crop-tops, and bubble swim rings. The bubble rings apparently allow them to fly in mid-air. They are physically identical except for their colors and the designs of their hats.

Ichika is a redhead with a green-striped tail, her top is white and her hat is green with white polka-dots.

Nika is blond with a red-striped tail, her top is red and her hat matches her tail.

Sanka has orange hair and a blue striped tail, both her top and hat are solid blue.

Yonka has pink hair and a brown-striped tail, her top is brown and her hat is white.

Yonka Two has dark brown hair and a yellow-striped tail, her top is black and her hat has jaguar-prints.

Personality
The five sisters tend to talk in a unique speech pattern. Ichika starts off first by saying a regular statement. Nika then states an exclamatory version of Ichika's statement. Sanka then states the opposite of the original statement. Yonka then questions the original statement. Lastly, Yonka Two then questions whether the original statement matters or not. An example of a typical routine:

Ichika: Luffy is a pirate.

Nika: Luffy is a pirate!

Sanka: Luffy isn't a pirate.

Yonka: Luffy might be a pirate.

Yonka Two: So what if Luffy's a pirate?

Other than that, they are cheerful and friendly and they usually stay close together.

History
They are first seen in Keimi's house when Luffy awakens after he and his crew flew through the bubble surrounding Fishman Island, fell into a current, and got separated. As Luffy, Sanji, Usopp, and Chopper get reacquainted with Keimi, the quintuplets give them their dried clothes. They are next seen in the Mermaid Cove, telling Keimi about the arrival of the royal gondola, and whether or not royalty was on board. They are then seen in Coral Hill when the residents start suspecting the Straw Hats for kidnapping mermaids. Later on, they hear the news of the Straw Hats "taking over" the Ryugu Palace.

After the battle for Fishman Island, the quintuplets are seen dancing at the banquet in the Ryugu Palace. When the Straw Hats finally leave Fishman Island, the quintuplets are there to bid them farewell.

Translation and Dub Issues
The quintuplets names are based on Japanese numbers. Ichika comes from Ichi meaning 1. Nika comes from Ni meaning 2. Sanka comes from San meaning 3. Lastly, Yonka comes from Yon meaning 4. The last sister's name, Yonka Two is just as is. This forms a joke as based on the first four sisters' names, there is a numerical pattern. Based on the pattern, Yonka Two's name would naturally be expected to be Goka from "Go" meaning "5", as Ussop points out at their introduction. Instead however, her name breaks the pattern.