Seira

Seira is a bluestriped angelfish mermaid and an employee of the Mermaid Cafe.

Appearance
Seira is a mermaid with brunette hair tied in a ponytail and a pink tail with purple marks. She wears a pair of shell headphones, a yellow bikini with blue flowery straps, a red pearl necklace and red lipstick.

Personality
Like all other mermaids, Seira is kind and caring, and is apparently fun loving. When meeting Luffy, Usopp, Sanji and Chopper for the first time she comments approvingly on their boldness of having entered Fishman Island illegally, stating that she loves pirates.

Abilities and Powers
As a mermaid, Seira can breath underwater, and they are generally considered the fastest swimmers in the world. She also appears to be a skilled dancer.

Fishman Island Arc
Seira and her friends first appeared in Mermaid Cove, welcoming the Straw Hat Pirates when Keimi brought them there for a visit. When the three princes arrived to inquire the crew's illegal entry into Fishman Island, the mermaids denied the crew was there, hiding them. However, when the crew's presence were made known anyways by Sanji's nosebleed and Hammond's attack, the princes made it clear that they were simply trying to deliver Jinbe's message to Monkey D. Luffy.

After the civil war between the Straw Hats and the New Fishman Pirates ended, Seira and her friends danced at the Ryugu Palace banquet in honor of the Straw Hats' victory and saw them off when they departed to the New World.

Trivia

 * Her name is the Japanese pronunciation of the word "sailor".