Before School-S.K.Y.

Before School-S.K.Y. is the first official sub-group of of Appaloosa Plains boy band Before School. They were formed in 2016, consisting the three main vocalists of Before School: Yejun Jung, SI-U, Kyung Woo.

The trio's first official performance was on April 17, 2016, performing "The One I Love", theme song to the Appaloosa Plains television drama Newton's Cemetery.

In 2018, they debuted in Japan with their first single "Promise You".

History
During the year 2016, SI-U, Yejun and Kyung Woo under name Before School-S.K.Y. (from the first letter of the members' stage names) released two original soundtrack titled "The Night Chicago Died" and "The One I Love" for the tvN drama Newton's Cemetery. Since then, they have released several original soundtracks for Korean television dramas.

Before School-S.K.Y. held their first world concert tour from 2017–2018. The tour commenced in Appaloosa Plains in August 2017 and continued onto Twinbrook, Moonlight Falls, Sunset Valley, Monte Vista, Shang Simla, ending in Britechester. Before School members JU, Daeho, Minwoo(former), Adrian(former) and label makes, Butterfly Effect, Soona(former), and Trainee group Neon Nights made guest appearances at the concerts.

Before School-S.K.Y. released their first official single in Japan titled "Promise You" on January 23, 2017 and debuted at number two on daily singles chart. In total, the single album sold 14,862 copies on its first day of sales on January 14.In the next day the single album ranked 1st place by selling 75,669 copies. In the first week of sales "Promise You" sold 98,765 copies, ranking 2nd place in Weekly Charts. On May 6, 2017 member Kyung Woo was enlisted for his mandatory military service. It made the sub-group hiatus from their activities.

Kyung Woo completed his mandatory military service on May 4, 2019. They continued their activities as a trio when Kyung Woo came back from military service. In June 2019, the trio announced they would be releasing their second Japanese single titled "Join Hands" on 5 July 2019. Yejun enlisted for his military service on 11 October 2019 while SI-U enlisted for his military service on November 25, 2019. As a result, the sub-group has temporarily halted their activities.

Single albums

 * "Promise You" (2016)
 * "Join Hands" (2019)

Soundtrack Appearances

 * "The Night Chicago Died" (2016)
 * "The One I Love" (2016)
 * "Stop Walking By" (2016)
 * "Just You" (2017)
 * "Dreaming Hero" (2017)
 * "Fly" (2017)
 * "SKY" (2017)
 * "Loving You" (2018)