You may prefer to use the Hangul tag, which is 윤하.
Younha (ko.: 고윤하 - Go Yoonha; hanja: 高潤荷; jap.: ユンナ - Yunna) born April 29, 1988 in Seoul, South Korea, is a K-Pop and J-Pop South Korean singer. She debuted in 2004 with the release of her first single, "ゆびきり" (Yubikiri).
Younha made her debut as an artist at the young age of sixteen. Nicknamed the "Oricon comet" for her success in Japan, she has released eight singles and two albums there with varying degrees of success. Several of her songs have been featured in anime/dramas.
Younha is signed to Epic Records, owned by Sony Music Japan. In South Korea, she is signed to Lion Media and Stam Entertainment.