Eryuell Island, also known as Eurel Island in foreign servers, is a home to elves. The elves that lived on the island were originally pacifistic and avoided all human conflict until they decided to help them. They hosted the Elven Corps, and sent one of their best troopers, Lire, to battle alongside humans to defeat Kaze'aze.
At first, the island was a hiding spot for elves when the Serdin/Kanavan war occurred. After the five years, some elves left to support the humans in the future uprisings. It could be possible that some humans actually live on Eryuell as well.
Eryuell Island is an uncharted area on the World Map, but it is likely to be in or around Bermesiah as stated by the story.
Ladmir Eryuell is an elf of Eryuell Island and Lire's older brother. He is the one who brought her up after they lost their parents. He is a calm individual with a great sense of responsibility and leadership and, despite his young age, stands as one of the major figures in Eryuell Island, holding great influence over the elves.
Myrielle Ariaden is another resident of Eryuell Island and Lire's childhood friend. Unlike Lire, she was carefree and wild, her antics often getting the both of them into scapes and accidents, but her archery skills almost rivaled that of Lire.
Myrielle had always wanted to leave Eryuell Island and see the rest of the world, but when the chance first goes to Lire, she tells Lire to "see the rest of the world for her."