BY2 is a duo from Singapore composed of twins Miko Bai Wei-Fen (白緯芬) and Yumi Bai Wei-Ling (白緯玲) (born March 23, 1992). Their duo band was named "BY2" after their surname "Bai" and that they are twin sisters and have a 10-year contract with Ocean Butterflies Music Pte Ltd. They debuted with their album "16未成年" on 21 July 2008. These sisters have been given different hairstyles for easy identification due to their uncanny resemblance. However, they claimed to be different in terms of personality. Miko has been described as more introverted and quiet while her sister Yumi, has been described as a more extroverted and outgoing person. Since young age, both of the sisters have been exposed to performing arts and have learned the violin, piano, ballet and many other styles of dancing. At the age of 13, both of them joined the Ocean Butterflies' Music Forest's "非常歌手" training course. The course aims to teach singer-wannabes how to perform on stage and techniques in singing and dancing. They graduated from the course clinching a "Best Costume Design" award. Billy Koh of Ocean Butterflies Music Pte Ltd noticed their talent and gave them a 10-year record deal. The duo moved to Taiwan in 2007 to further their career.