"U" is the first single by Super Junior, released on June 7, 2006. It's the group's first release with the newly added member Kyuhyun.
- Endless Moment
- Lovely Day
- Lyrics: Taehoon
- Composition: Wi Gook-gok
- Arrangement: Hwang Sung-je
- The single peaked at #1 on the monthly MIAK K-pop album charts and sold 91,416 copies by 2008.
- The song won a total of five music recognitions, being Super Junior's most successful single in the music charts until the release of "Sorry, Sorry" in March 2009.
- Super Junior-M, Super Junior's Mandopop sub-unit, released a Chinese version of the song in their first album Me.
- It marks their first release as a permanent group (ending their status as a project group) and the first release with their final line up with addition of the thirteenth member, Kyuhyun.